Forces and motion

• Physics
• Upper Secondary (Key Stage 4)
• GCSE

Forces and motion

Chapter 10

Drag the symbol (blue) to the name (red)

mass

change in momentum

final velocity

initial velocity

force

momentum

acceleration

m

Δp

F

u

v

a

p

Drag the units (blue) to the symbol(red)

m

Δp

v

u

F

p

a

m/s

m/s2

m/s

kgm/s

kgm/s

kg

N

Force, mass and acceleration

Newton's 2nd Law tells us that...

1. the greater the force, the smaller the acceleration
2. the greater the force, the greater the acceleration
3. the greater the mass, the smaller the acceleration
4. the greater the mass the greater the acceleration

A motorcycle has a mass of 200 kg, what force is needed to give it an acceleration of 7 m/s2?

1. 28.6 N
2. 1400 N
3. 1400 kgm/s
4. 140 N

A car has a mass of 1500 kg, what force is needed to give it an acceleration of 4 m/s2?

1. 6000 N
2. 60000 N
3. 6000 kg
4. 600 m/s2

What is the force needed to accelerate a 250 kg motorbike at 5 m/s2?

1. 125 N
2. 50 N
3. 1250 N
4. 500 N

The engine of a 300 kg motorbike produces a force of 1000 N. What is its acceleration?

1. 300000 m/s2
2. 0.3 m/s2
3. 3.3 m/s
4. 3.3 m/s2

The mass of a pilot and her seat in a fighter jet is 125 kg. When she ejects, she is subjected to an acceleration of 120 m/s2. What is the force acting on the pilot and the ejector seat?

1. 1500 kg
2. 1500 N
3. 15000 m/s
4. 15000 N

A car's engine produces a force of 1000 N and the car accelerates at 2.5 m/s2. What is the mass of the car?

1. 400 N
2. 4000 N
3. 4000 kg
4. 400 kg

A man accelerates at 15 m/s2 when doing the high jump using a force of 1200 N. What is his mass?

1. 18,000 kg
2. 0.0125 kg
3. 80 kg
4. 800 kg

Terminal velocity

When a skydiver jumps out of a plane...

1. There is lots of air resistance
2. There is no air resistance

When a skydiver jumps out of a plane, there is no air resistance, so the resultant force is...

1. Downwards
2. Upwards

When a skydiver jumps out of a plane, there is no air resistance, so the resultant force is downwards and the skydiver...

1. Accelerates downwards
2. Accelerates upwards
3. Decelerates
4. Falls at a constant speed

The faster the skydiver falls...

1. Air resistance doesn't change
2. The smaller the air resistance
3. There is still no air resistance
4. The bigger the air resistance

Eventually, air resistance becomes equal to weight so the skydiver falls at...

1. interval velocity
2. consistent velocity
3. terminal velocity
4. constant velocity

The skydiver then opens their parachute. The larger the surface area of a skydiver's parachute...

1. The smaller the air resistance
2. The bigger the air resistance

When a skydiver opens their parachute, air resistance is bigger than weight so...

1. the resultant force is downwards
2. the resultant force is upwards
3. there is no resultant force
4. air resistance and weight aren't important

When a skydiver opens their parachute, air resistance is bigger than weight so the resultant force is upwards and the skydiver...

1. accelerates
2. decelerates
3. there is no change in velocity

Which number represents where weight is equal to air resistance?

1. 1
2. 2
3. 4
4. 8

Which number represents where weight is bigger than air resistance?

1. 1
2. 2
3. 5
4. 6

Which number represents where weight is smallerthan air resistance?

1. 2
2. 4
3. 6
4. 7

Momentum

Momentum is a

1. scalar
2. vector

A rugby player has a mass of 85 kg and sprints at 5 m/s. What is his momentum?

1. 425 m/s2
2. 17 kgm/s
3. 17 m/s2
4. 425 kgm/s

A truck has a mass of 5000 kg and a velocity of 5m/s. Calculate its momentum.

1. 1000 kgm/s
2. 2500 kgm/s
3. 10000 kgm/s
4. 25000 kgm/s

The lorry is about to hit the stationary car. Assume they stick together. How fast will they move afterwards?

1. 0 kg m/s
2. 3500 kg
3. 55000 kg m/s
4. 15.7 m/s

Impact forces and car safety

A car has a mass of 2000 kg. Its velocity changes from 5 m/s to 10 m/s in 5 seconds. What force causes this change in velocity?

1. 200 N
2. 200 kg
3. 2000 kg
4. 2000 N

A toy car has a mass of 2 kg. Its velocity changes from 2 m/s to 5 m/s, with a force of 4 N. How long does this change in velocity take?

1. 10 s
2. 1.5 s
3. 2.5 s
4. 5 s

A force of 500 N acts on a 1000 kg car for 10 s. Its initial velocity was 2 m/s. Calculate its final velocity.

1. 4 m/s
2. 5 m/s
3. 6 m/s
4. 7 m/s

To reduce the impact force...

1. decrease the time taken
2. increase the time taken
3. decrease the surface area
4. increase the surface area

The picture shows rubber tiles used for playground flooring. Explain how these can reduce injury to children.