Motion and it's Measurements

Question 1

What is speed

Answer 1

How fast an object is moving, regardless of direction

Question 2

What is displacement

Answer 2

How far an object has travelled from its starting point in a given direction

Question 3

What is velocity

Answer 3

Rate of change of displacement

Question 4

What is acceleration

Answer 4

Rate of change of velocity

Question 5

What is the equation for velocity

Answer 5

v = Δs/Δt

Velocity (m/s) = Δ Displacement (m)/ Δ Time (s)

Question 6

What is the equation for acceleration

Answer 6

a = Δv/Δt

Acceleration (m/s^2) = ΔVelocity /ΔTime

Question 7

What is instantaneous velocity

Answer 7

The velocity of an object at a specific point in time

It can be found from a displacement-time graph by drawing a tangent to the graph at the specific time and calculating the gradient

Question 8

What is average velocity

Answer 8

The velocity of an object over a specified time frame

It can be found by dividing the final displacement by the time taken

Question 9

Describe a Distance-Time Graph

Answer 9

Question 10

What is uniform acceleration

Answer 10

When the acceleration of an object is constant

Question 11

Describe uniform and non-uniform acceleration on an acceleration-time graph and the area under the graph

Answer 11

Question 12

Describe a Velocity-Time Graph

Answer 12

Question 13

What are the 4 SUVAT questions

Answer 13

• v = u + at
• s = (u + v) / 2 x t
• s = ut + ½ at^2
• v^2 = u^2 + 2as

Question 14

When can SUVAT equations be used

Answer 14

When object is moving at uniform acceleration

Question 15

How do you approach projectile motion questions

Answer 15

• Remember horizontal and vertical motion can be evaluated separately using the SUVAT equations
• Remember in horizontal acceleration = 0
• Remember in vertical initial velocity = 0 (If fired horizontally)

Question 16

How do you approach projectile motion questions when an object is projected at an angle

Answer 16

• Resolve the velocity into horizontal and vertical components
• Evaluated the horizontal and vertical components separately using the SUVAT equations

Question 17

What is a free fall

Answer 17

When an object experiences an acceleration due to gravity

Question 18

What is friction

Answer 18

A force which opposes the motion of an object (known as drag in fluids)

Question 19

Which energy transfers does friction result in

Answer 19

Friction converts kinetic energy into other forms such as heat and sound

Question 20

What happens to air resistance when the speed of an object increases

Answer 20

Air resistance increases

Question 21

What is lift

Answer 21

• An upwards force that acts on an object moving through a fluid
• Acts perpendicular to the direction of fluid flow

Question 22

When is lift caused

Answer 22

When an object in a fluid causes the fluid flowing over it to change direction

Question 23

When is terminal speed achieved

Answer 23

• Occurs when the frictional forces acting on an object and driving forces are equal
• Therefore there is no resultant force and so no acceleration
• So the object travels at a constant speed

Question 24

Describe how a moving object reaches terminal speed

Answer 24

• Constant driving force (e.g gravity) causes acceleration.
• As speed increases, the frictional force increases. This reduces the resultant force
• Therefore reducing the acceleration
• Eventually, the frictional force equals the driving force and terminal speed is achieved

Question 25

Describe the effect of air resistance on the trajectory of a projectile

Answer 25

Without air resistance it will travel further

Question 26

What is needed for a moving object to reach a terminal velocity

Answer 26

• Driving force that stays constant
• Frictional force that increases with speed

Question 27

What factors increase a moving object’s terminal speed

Answer 27

• Increase the driving force (e.g. bigger engine)
• Reduce the frictional force (e.g. more streamlined object)