2B1 Forces and Motions Flashcards

Explore how force and motion are connected to key concepts such as speed, buoyancy, and gravity. (82 cards)

1
Q

Define:

Motion

A

The change in the position of an object over time.

It occurs when an object moves from one place to another and can be described in terms of displacement, velocity, and acceleration.

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2
Q

What is one-dimensional motion?

A

Motion along a straight line.

The object moves in only one direction, like a car driving down a straight road.

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3
Q

What is motion in two dimensions?

A

Motion in a plane (horizontal and vertical).

This kind of motion involves movement in both the x and y directions, such as a projectile launched into the air.

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4
Q

True or False:

In one-dimensional motion, an object can only move forwards or backwards.

A

True

One-dimensional motion is restricted to a single axis, meaning the object only moves in one direction.

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5
Q

What is displacement?

A

Shortest distance from start to end, with direction.

It is a vector quantity because it considers both the distance and the direction of the straight line between the starting and ending points.

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6
Q

How is distance different from displacement?

A
  • Distance is the total path length.
  • Displacement is the straight-line distance.

Distance is scalar, while displacement accounts for direction and is a vector quantity.

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7
Q

True or False:

Displacement can be zero even if distance is not zero.

A

True

Walking in a circle results in a distance traveled but zero displacement since you end where you started.

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8
Q

Define:

scalar quantity

A

A quantity with only magnitude.

Scalars are described by a number (magnitude) only, without any directional component. Examples include mass, time, and temperature.

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9
Q

What is speed?

A

Distance traveled per unit time.

Speed is a scalar and doesn’t account for direction, unlike velocity, which is a vector quantity.

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10
Q

True or False:

Distance and displacement are both scalar quantities.

A

False

While distance is scalar, displacement includes direction and is therefore a vector quantity.

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11
Q

What is the formula for calculating speed?

A

Distance / Time

It tells us how fast something moves, and is calculated by dividing total distance by total time.

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12
Q

Define:

Velocity

A

The rate of change of displacement.

Unlike speed, velocity is a vector, meaning it also includes the direction of movement.

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13
Q

Fill in the blank:

Acceleration occurs when there is a change in _______.

A

velocity

Acceleration is defined as any change in the object’s velocity, whether in speed or direction.

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14
Q

What is the formula for acceleration?

A

a = Δv / t

Acceleration measures how quickly an object’s velocity changes over time. It is calculated by dividing the change in velocity (Δv) by the time (t) taken for this change.

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15
Q

A car travels 200 meters in 10 seconds. What is its speed?

A

20 m/s

Using Speed = Distance / Time, Speed = 200 meters / 10 seconds = 20 m/s.

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16
Q

Fill in the blank:

The force required to accelerate a 5 kg object by 3 m/s² is ______ N.

A

15

Use the formula Force = Mass × Acceleration. In this case, Force = 5 kg × 3 m/s², resulting in 15 N.

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17
Q

True or False:

Speed is the same as velocity.

A

False

Speed is a scalar, while velocity is a vector (it has both magnitude and direction).

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18
Q

What is work?

A

The transfer of energy through displacement.

Work is calculated as W = F × d × cos(θ), where F is the force, d is the displacement, and θ is the angle between them.

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19
Q

True or False:

Work is done when there is no displacement in the direction of the force.

A

False

Work requires a displacement in the direction of the applied force.

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20
Q

What is momentum (p)?

A

The product of mass and velocity.

Momentum is a vector and represents how much motion an object has, given its mass and velocity. It is represented by p.

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21
Q

How is momentum calculated?

A

p = mv

Momentum(p) is the product of an object’s mass (m) and its velocity (v). It represents the quantity of motion an object has, and the greater the mass or velocity, the greater the momentum.

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22
Q

True or False:

Momentum is a scalar quantity.

A

False

Momentum includes both magnitude and direction, so it is a vector quantity.

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23
Q

Define:

Force

A

A push or pull that causes a change in motion.

It is a vector quantity and can change an object’s speed or direction.

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24
Q

What are contact forces?

A

Forces acting when two objects are in direct contact.

Examples include friction, normal force, tension, and applied force.

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25
What is **friction**?
A force that **opposes motion** between surfaces. ## Footnote It depends on the nature of the surfaces and the normal force.
26
# True or False: Friction **always** opposes motion.
True ## Footnote Friction **resists** relative motion between two surfaces, no matter the direction of movement.
27
What is the **normal force**?
A force **perpendicular** to the surface of contact. ## Footnote It acts to **counterbalance** the weight of an object resting on a surface, preventing it from accelerating through the surface.
28
How does friction **change** with surface area?
Friction is mostly **independent** of surface area. ## Footnote While surface area does play a role, friction is more strongly influenced by the nature of the surfaces and the normal force.
29
# Fill in the blank: \_\_\_\_\_\_\_ is the **force** in a rope or string.
Tension ## Footnote **Tension** is a *pulling* force transmitted through flexible objects like ropes or cables when they are stretched.
30
What is **projectile motion**?
Motion of an object under the **influence** of gravity and air resistance. ## Footnote This motion combines horizontal constant velocity and vertical acceleration due to gravity, resulting in a parabolic trajectory.
31
# True or False: Horizontal and vertical motions are **independent** in projectile motion.
True ## Footnote The horizontal motion is **unaffected** by gravity, while the vertical motion is influenced by gravitational acceleration.
32
What **shape** is the trajectory in projectile motion?
Parabolic ## Footnote The combination of constant horizontal velocity and accelerated vertical motion results in a curved path.
33
What does **Newton’s First Law** state?
An object will **remain** at rest or in uniform motion unless acted upon by an external force. ## Footnote This law is also called the *Law of Inertia*. It emphasizes that objects resist changes in their state of motion unless a force causes a change.
34
# Define: Inertia
The tendency of an object to **resist** changes in its motion. ## Footnote It is directly *related* to an object's mass; the greater the mass, the greater the inertia.
35
What does the **law of inertia** explain about the motion of a car when you suddenly stop?
The passengers **continue** moving forward. ## Footnote According to *Newton’s First Law*, the passengers' bodies resist the change in motion and keep moving while the car stops.
36
What does **Newton’s Second Law** describe?
The **relationship** between force, mass, and acceleration. ## Footnote It states that the acceleration of an object is *directly proportional* to the net force acting on it and inversely proportional to its mass (F = ma).
37
# Fill in the blanks: According to Newton's Second Law, the **acceleration** of an object is \_\_\_\_\_\_\_ proportional to the net force and \_\_\_\_\_\_\_ proportional to its mass.
directly, inversely ## Footnote This relationship means that for the same force, a larger mass results in less acceleration, while more force results in more acceleration.
38
# True or False: If you apply a **constant force** to two objects with different masses, the object with the greater mass will have greater acceleration.
False ## Footnote According to *Newton’s Second Law*, the object with the greater mass will have **less acceleration** for the same force.
39
What is the **formula** to calculate force?
Mass × Acceleration ## Footnote This formula is *derived* from *Newton's Second Law of Motion*, stating that the force on an object is the product of its mass and acceleration.
40
What is the **acceleration** of a 10 kg object when a force of 50 N is applied?
5 m/s² ## Footnote Using *F = ma*, we rearrange to a = F/m. So, a = 50 N / 10 kg = **5 m/s²**.
41
What does **Newton’s Third Law** state?
For every action, there is an **equal and opposite reaction**. ## Footnote This law explains that forces always come in pairs. If object A exerts a force on object B, object B exerts an equal force in the opposite direction on object A.
42
# True or False: According to Newton’s Third Law, the action and reaction forces act on the **same** object.
False ## Footnote The action and reaction forces act on two **different** objects, but they are always equal and opposite.
43
What is the **net force** acting on a 20 kg object with an acceleration of 2 m/s²?
40 N ## Footnote Using F = ma, the net force is F = 20 kg × 2 m/s² = **40 N**.
44
What happens when the **force on an object is doubled**?
The **acceleration doubles**, assuming mass is constant. ## Footnote This follows from Newton's Second Law: F = ma. When F increases, so does a, as long as m remains the same.
45
# True or False: According to Newton’s First Law, an object can continue moving **forever** if no force acts on it.
True ## Footnote In space, with no friction or other forces, an object would continue at a *constant velocity* indefinitely.
46
How do action and reaction forces **apply** when a swimmer pushes against the wall of a pool?
The swimmer pushes on the wall, and the **wall pushes the swimmer forward**. ## Footnote The force the swimmer exerts on the wall has an equal and opposite reaction, propelling the swimmer forward.
47
# True or False: Action and reaction forces **cancel** each other out.
False ## Footnote According to *Newton’s Third Law*, every action has an equal and opposite reaction. However, since these forces act on separate objects, they do not cancel but instead **influence** the motion of different bodies.
48
What is **centripetal acceleration**?
Acceleration directed toward the **center** of a circular path. ## Footnote It is calculated as a = v² / r, where v is the speed and r is the radius of the circle.
49
What **provides** centripetal force?
Tension, gravity, or friction. ## Footnote *Centripetal force* is the net inward force that keeps an object moving in a circle, and can be provided by different forces depending on the situation (e.g., tension in a rope or gravitational force in orbit).
50
# Fill in the blank: Centripetal force **keeps** an object in \_\_\_\_\_\_\_ motion.
circular ## Footnote Without centripetal force, objects would move in straight lines due to inertia, as described by Newton's First Law.
51
# Define: Buoyancy
An **upward** force exerted by a **fluid**. ## Footnote Buoyancy **opposes** an object's weight, allowing it to float or sink depending on its density.
52
What **principle** explains buoyancy?
Archimedes' Principle ## Footnote *Archimedes' Principle* states that an object **submerged** in a fluid experiences an *upward buoyant force* equal to the weight of the displaced fluid. This explains why some objects float while others sink, depending on their density relative to the fluid.
53
What **determines** if an object floats or sinks?
Its **density** compared to the fluid’s density. ## Footnote An object will float if its density is *less* than the density of the fluid; otherwise, it will sink.
54
What is the **ratio** of a substance's density to water's density?
Relative density ## Footnote If the *relative density* is greater than 1, the substance is denser than water; if less than 1, it's less dense.
55
# True or False: Relative density is a **unitless quantity**.
True ## Footnote Since it’s a ratio of *two densities*, relative density has no units.
56
What is the **relationship** between buoyancy and relative density?
If relative density is less than 1, the object **floats**; if greater than 1, it **sinks**. ## Footnote Buoyancy relies on the weight of displaced fluid, which is affected by the object's relative density.
57
What is **weight**?
The **force** exerted on an object due to gravity. ## Footnote Unlike mass, weight can vary due to the object's location. Weight is calculated using the formula: *Weight = Mass × Acceleration* due to gravity (W = mg).
58
What is the **difference** between weight and mass?
* **Mass** is the amount of matter. * **Weight** is the force of gravity on an object. ## Footnote Mass is constant and measured in kilograms (kg), while weight depends on the gravitational force acting on the object and is measured in newtons (N).
59
# True or False: Mass **changes** depending on the location of an object in the universe.
False ## Footnote Mass is a scalar quantity that remains constant **regardless** of location, while weight changes depending on gravitational force.
60
What **units** are used to measure mass and weight?
* Mass is in **kilograms** (kg) * Weight in **newtons** (N) ## Footnote The unit for weight (newtons) is derived from the formula W = mg, where g is acceleration due to gravity.
61
What is the **gravitational constant** (G)?
6.674 × 10⁻¹¹ N·m²/kg² ## Footnote The gravitational constant is used in the equation for *Newton’s Law of Universal Gravitation*.
62
# Fill in the blank: According to **Newton's Law of Universal Gravitation**, the gravitational force between two objects \_\_\_\_\_\_\_ as the distance between them increases.
decreases ## Footnote The force is *inversely proportional* to the square of the distance between the centers of the two objects.
63
# True or False: The gravitational force between two objects **increases** if their masses decrease.
False ## Footnote According to the law of universal gravitation, the force increases with mass, but decreases with the square of the distance between objects.
64
What is a **gravitational field**?
A **region** where gravity exerts an attractive force on objects. ## Footnote The strength of a gravitational field depends on the mass of the object creating the field and the distance from it.
65
How does the Earth's gravity field **affect** objects near its surface?
It **pulls objects toward the center of the Earth**, giving them weight. ## Footnote This gravitational force is **responsible** for keeping objects, including people, anchored to the Earth’s surface.
66
# True or False: A gravity field is **stronger** the farther you are from the source mass.
False ## Footnote The strength of the gravity field **decreases** as you move further from the source mass, following an inverse square law.
67
What is the **acceleration** due to gravity on Earth (in m/s²)?
9.8 m/s² ## Footnote This is the *constant acceleration* that objects experience when falling freely near Earth's surface, neglecting air resistance.
68
How is the force of gravity **calculated** on an object?
W = mg ## Footnote **Weight** is the mass of the object multiplied by the local acceleration due to gravity.
69
# True or False: An object's mass is **always** greater on the Moon than on Earth.
False ## Footnote Mass is **constant** everywhere in the universe. What changes is the object's weight due to the difference in gravity.
70
How does gravity **affect** objects in freefall?
It **accelerates** all objects equally without air resistance. ## Footnote This is why objects like a feather and a hammer, in a vacuum, fall at the **same** rate.
71
What is the **relationship** between gravity and the orbits of planets?
Gravity keeps planets in their **elliptical orbits** around the Sun. ## Footnote The Sun’s gravitational pull **continuously** pulls planets, preventing them from flying off into space.
72
How does the acceleration due to gravity **change** with altitude?
The **farther** from Earth's surface, the **weaker** the gravitational pull and acceleration. ## Footnote At high altitudes, **g** decreases slightly due to the increased distance from the Earth’s center.
73
# True or False: Gravity **only** affects objects on Earth.
False ## Footnote Gravity is a *universal force* and affects all matter, both on Earth and throughout the universe.
74
How does the mass of an object **affect** the gravitational force it exerts?
The **greater** the mass, the **stronger** the gravitational force it exerts. ## Footnote According to Newton's law of universal gravitation, the force increases as the mass increases.
75
# Define: vector quantity
A quantity that has both **magnitude and direction**. ## Footnote Unlike *scalar quantities*, which only have magnitude, *vector quantities* are fully described by both the size (magnitude) and the direction in which they act.
76
What are the **components** of a vector?
The **projections** of a vector along coordinate axes. ## Footnote Components are typically **horizontal (x)** and **vertical (y)** and can be found using trigonometry or by breaking the vector into parts.
77
What is the **formula** for calculating the force from a vector?
F = m × a ## Footnote where: **m** is mass **a** is acceleration
78
What are examples of **vector quantities**?
* displacement * velocity * acceleration * force * momentum
79
What is the **difference** between a vector and a scalar?
A **vector** has both magnitude and direction; a **scalar** has only magnitude. ## Footnote Vectors include force, velocity, and displacement, while scalars include mass, temperature, and time.
80
What are examples of **scalar quantities**?
* mass * speed * time * distance * energy
81
# True or False: The magnitude of a force is **independent** of the direction.
False ## Footnote The direction of a force **affects** how an object moves or accelerates, making it essential to the force's impact.
82
What is the **resultant** of two vectors?
The **vector sum** of the two vectors. ## Footnote The resultant can be found using the *head-to-tail method* or by *adding* their components.