Dynamics

Question 1

What is dynamics in physics?

Answer 1

Dynamics is a branch of mechanics that focuses on the motion of bodies under the action of forces.

Question 2

What is a scalar quantity?

Answer 2

A scalar quantity is fully described by its magnitude only.

Question 3

Give three examples of scalar quantities.

Answer 3

Time, Mass, Energy.

Question 4

What is a vector quantity?

Answer 4

A vector quantity is described by both magnitude and direction.

Question 5

Give three examples of vector quantities.

Answer 5

Velocity, Displacement, Force.

Question 6

What is displacement?

Answer 6

Displacement is a distance with a direction.

Question 7

What is velocity?

Answer 7

Velocity is a speed with a direction.

Question 8

What is the equation relating displacement, velocity, and time?

Answer 8

Displacement = Average Velocity x Time.

Question 9

How do you calculate average velocity?

Answer 9

Average Velocity = Displacement / Time.

Question 10

What must you consider when adding vectors?

Answer 10

You must consider both magnitude and direction.

Question 11

What is a scale diagram used for in vectors?

Answer 11

A scale diagram is used to draw vectors to scale and determine the resultant vector.

Question 12

What tool is commonly used with scale diagrams to calculate vector directions?

Answer 12

Trigonometry (SOHCAHTOA).

Question 13

What mathematical method can be used to calculate resultant vectors?

Answer 13

Pythagoras’ theorem.

Question 14

How is acceleration calculated on a velocity-time graph?

Answer 14

Acceleration is calculated by finding the gradient of the line, using m = (y2 - y1) / (x2 - x1).

Question 15

How do you calculate displacement from a velocity-time graph?

Answer 15

Displacement is found by calculating the area under the line.

Question 16

What is the formula for the area of a triangle?

Answer 16

Area of a triangle = 1/2 base x height.

Question 17

What is the formula for the area of a rectangle?

Answer 17

Area of a rectangle = base x height.

Question 18

What is the definition of acceleration?

Answer 18

Acceleration is the change in velocity over time.

Question 19

What is the formula for acceleration?

Answer 19

a = (v - u) / t.

Question 20

What are the units of acceleration?

Answer 20

Meters per second squared (ms^-2).

Question 21

What does a slope on a velocity-time graph indicate?

Answer 21

A slope on a velocity-time graph indicates acceleration or deceleration.

Question 22

How do you calculate acceleration from a velocity-time graph?

Answer 22

You calculate acceleration by finding the gradient using m = (y2 - y1) / (x2 - x1).

Question 23

Describe an experiment to calculate the acceleration of a car rolling down a hill.

Answer 23

Use a timer, two light gates, and a car with a card of known length. Measure the time taken to cut each gate and calculate velocity at each gate. Use the change in velocity over the time between the gates to find acceleration.

Question 24

What equipment is needed to measure acceleration in the described experiment?

Answer 24

A timer, two light gates, and a car with a card of known length.

Question 25

How is velocity at each light gate calculated?

Answer 25

Velocity is calculated by dividing the length of the card by the time taken to cut the light gate.

Question 26

How is acceleration calculated from the velocities measured at the light gates?

Answer 26

Acceleration is calculated by dividing the change in velocity by the time between the two gates.

Question 27

What does Newton’s First Law state?

Answer 27

An object at rest or moving at a constant velocity in a straight line will remain that way unless acted upon by an unbalanced force.

Question 28

Give an everyday example of Newton’s First Law.

Answer 28

A person standing still will remain standing still unless pushed.

Question 29

What does Newton’s Second Law state?

Answer 29

Force equals mass times acceleration (F = ma).

Question 30

What is the formula for force?

Answer 30

Force = Mass x Acceleration.

Question 31

What are the units for force, mass, and acceleration?

Answer 31

Force is in Newtons (N), mass in kilograms (kg), and acceleration in meters per second squared (ms^-2).

Question 32

What does Newton’s Third Law state?

Answer 32

Every action has an equal and opposite reaction.

Question 33

Give an example of Newton’s Third Law.

Answer 33

A rocket launches by pushing exhaust gases downward, and the rocket is pushed upward.

Question 34

What is the difference between weight and mass?

Answer 34

Mass is the amount of matter in an object; weight is the force due to gravity on that mass.

Question 35

What is the formula for weight?

Answer 35

Weight = Mass x Gravitational Field Strength (W = m x g).

Question 36

What is the gravitational field strength on Earth?

Answer 36

9.8 Nkg^-1.

Question 37

What is free fall?

Answer 37

Free fall is when gravity is the only force acting on an object.

Question 38

What is terminal velocity?

Answer 38

Terminal velocity is the maximum velocity reached when air resistance balances the force of gravity, resulting in no further acceleration.

Question 39

What is the principle of conservation of energy?

Answer 39

Energy cannot be created or destroyed, only converted from one form to another.

Question 40

Give three examples of different types of energy.

Answer 40

Light, Heat, Kinetic.

Question 41

When a car runs, what energy conversion takes place?

Answer 41

Chemical energy from the fuel is converted into kinetic energy.

Question 42

What is work done?

Answer 42

Work done is the energy required to move an object a certain distance.

Question 43

What is the formula for work done?

Answer 43

Ew = Force x Distance (Ew = F x d).

Question 44

Why is energy sometimes 'lost' during energy conversions?

Answer 44

Energy can be lost to other forms like heat due to frictional forces.

Question 45

What is kinetic energy?

Answer 45

Kinetic energy is the energy of movement.

Question 46

What is the formula for kinetic energy?

Answer 46

Kinetic Energy = 1/2 x mass x velocity^2.

Question 47

In what unit is kinetic energy measured?

Answer 47

Joules (J).

Question 48

Give an example of chemical energy being converted into kinetic energy.

Answer 48

When an animal moves, chemical energy from food is converted into kinetic energy.

Question 49

What is gravitational potential energy (GPE)?

Answer 49

Gravitational potential energy is the energy gained when an object is lifted away from a gravitational force.

Question 50

What is the formula for gravitational potential energy?

Answer 50

Gravitational Potential Energy = Mass x Gravitational Field Strength x Height (Ep = mgh).

Question 51

What is the gravitational field strength on Earth?

Answer 51

9.8 m/s^2.

Question 52

What does a Newton’s Cradle demonstrate about energy?

Answer 52

It shows the conversion of gravitational potential energy into kinetic energy and vice versa.

Question 53

How can kinetic and gravitational potential energy formulas be combined?

Answer 53

They can be combined when solving for missing values, as both are measured in Joules.

Question 54

What is projectile motion?

Answer 54

Projectile motion is the motion of an object where gravity is the only force acting on it, involving both horizontal and vertical motion.

Question 55

What two types of motion must be combined for projectile motion problems?

Answer 55

Horizontal velocity and vertical acceleration.

Question 56

What force causes vertical acceleration in projectile motion?

Answer 56

Gravity causes vertical acceleration.

Question 57

What is the acceleration due to gravity on Earth?

Answer 57

9.8 m/s^2.

Question 58

In projectile motion, which motion determines the time an object is in the air?

Answer 58

Vertical motion determines the time in the air.

Question 59

What formula is used to calculate horizontal velocity?

Answer 59

d = s × t, where d is distance, s is speed, and t is time.

Question 60

Does horizontal velocity change during projectile motion (ignoring friction)?

Answer 60

No, horizontal velocity remains constant.

Question 61

What determines when a projectile stops moving horizontally?

Answer 61

The time it hits the ground, determined by vertical motion.

Question 62

How can you calculate the distance traveled horizontally by a projectile?

Answer 62

Use the horizontal velocity and multiply it by the time the object is in the air.

Question 63

Why must horizontal and vertical motions be combined in projectile motion calculations?

Answer 63

To solve for unknown values like distance traveled or time of flight.