Unit 1

Question 1

Types of motion graphs

Answer 1

Displacement-time, Velocity-time, Acceleration-time

Question 2

Displacement-time graph features

Answer 2

Slope is velocity, y-intercept is initial displacement, curved line means acceleration, zero slope means rest

Question 3

Velocity-time graph features

Answer 3

Slope is acceleration, y-intercept is initial velocity, curved line means non-uniform acceleration, zero slope means constant velocity, area under the curve gives change in displacement

Question 4

Acceleration-time graph features

Answer 4

Slope is meaningless, y-intercept is initial acceleration, zero slope means constant acceleration, area under curve gives change in velocity

Question 5

Density definition

Answer 5

Amount of mass per unit volume

Question 6

How to get density of a regularly shaped object

Answer 6

Use the respective mathematical formula

Question 7

How to get density of an irregularly shaped object

Answer 7

Use a measuring cylinder. Fill half of it with water, taking note of the original measurement. Insert the object in, and take note of the final measurement. Subtract the final measurement by the initial measurement, and the answer would be the object’s water volume. Convert the water volume to real volume then

Question 8

Force definition

Answer 8

A force is an external agent capable of changing a body’s state of motion. (SI: Newtons, Vector Quantity).

Question 9

Resultant force definition

Answer 9

Vector sum of the forces acting on a body

Question 10

Newton’s first law (Inertia)

Answer 10

A body will remain at rest or move with constant velocity unless acted on by a resultant force

Question 11

Types of Inertia

Answer 11

1. Inertia of Rest - Tendency of an object to resist change in its state of rest
2. Inertia of Direction - The tendency of an object to resist changes in its direction of motion
3. Inertia of Movement - The tendency of an object to resist changes in its state of motion

Question 12

Newton’s second law

Answer 12

The resultant force on an object is directly proportional to its acceleration (F = ma)

Question 13

Newton’s third law conditions

Answer 13

1. Same type of force
2. Same magnitude
3. Opposite direction
4. Acting on different objects

Question 13

Newton’s third law

Answer 13

For every reaction, there is an equal and opposite reaction. If the action is on one body, the reaction will be on the other.

Question 14

What are contact forces (give examples)

Answer 14

Forces which act between objects that are physically touching

Examples:
- Friction
- Fluid Resistance
- Tension
- Normal Force
- Spring Force

Question 15

What are non-contact forces (give examples)

Answer 15

Forces which act from a distance, without any physical contact between bodies, most likely due to the action of a field.

Examples:
- Gravitational Force
- Electrostatic Force
- Magnetic Force

Question 16

What is the role of frictional forces?

Answer 16

To oppose the motion of an object

Question 17

What are the mechanics behind fluid resistance

Answer 17

Assume a body is skydiving
1. The air particles collide with the parachute, and through doing so, transfer their momentum to their parachute
2. There is higher pressure underneath due to the lower acceleration of air and lower pressure above due to the higher acceleration of air (Bernoulli’s principle), which overall creates an upwards force, thus adding on to the fluid resistance.

Question 17

What is the mechanic behind surface friction

Answer 17

Imperfections in the surfaces of the interacting objects rub and interlock with each other, which creates surface friction

Question 18

What are the two types of surface friction

Answer 18

1. Static Friction: The frictional force acting on a body at rest.
2. Dynamic Friction: The frictional force acting on a body in a state of motion.

Question 19

What is limiting friction

Answer 19

The maximum value the static friction can reach

Question 20

Why is the limiting friction’s value always bigger than the value of the dynamic friction

Answer 20

Because there are more forces at work keeping an object stationary than there are resisting the motion of an object.

Question 20

Describe a friction-applied force graph

Answer 20

The static friction rises, then a drop is produced as a result of the static friction being broken, and then the line is constant which transitions the friction to dynamic friction.

Question 21

What does Hooke’s law state and what is the formula

Answer 21

It states that the force exerted by a spring is directly proportional to the displacement from its equilibrium position. This applies upto the limit of proportionality.

F = -kx

Question 22

What is the spring constant (K)

Answer 22

The spring constant is a measure of the stiffness of a spring.

Question 23

Does every material have a different force-extension graph?

Answer 23

Yes, due to each material having different spring constants through factors such as brittleness, ductility etc.

Question 24

What does the slope of a force-extension graph give (the part that obeys Hooke's law)

Answer 24

Spring Constant (K)

Question 25

Definition of momentum, formula, SI unit

Answer 25

The product of mass and velocity. - p = mv - SI = kgms^-1

Question 26

What does the principle of conservation of linear momentum state

Answer 26

The total linear momentum before a collision is equal to the total linear momentum after the collision, unless the system is acted on by a resultant force.

Question 27

What is the centre of mass

Answer 27

It is a position defined relative to an object or systems of objects. This position is the average of all of the parts of the system's positions.