Forces P2

Question 1

What is Newton’s second law of motion

Answer 1

• The acceleration of an object is PROPORTIONAL to the resultant force acting on the object (if we have a greater force, we have a greater acceleration)
• and INVERSELY PROPORTIONAL to the mass of the object (if the mass is larger then the acceleration will be smaller)

Question 2

Force needed to accelerate an object equation

Answer 2

Force (n) = mass (kg) x acceleration (m/s squared)

Question 3

Road transport speed, acceleration and force

Answer 3

• on main road, cars travel at 13 m/s in the UK
• on a motorway 30 m/s
• accelerating from a main road to a motorway is usually 2 m/s squared
• for a typical family car, this would require a force of 2000N

Question 4

What is the property called when objects will stay still or keep the same motion unless you apply a resultant force

Answer 4

Inertia

Question 5

What is the inertial mass

Answer 5

• A measure of how difficult it is to change the velocity of an object
• the larger the inertial mass, the greater the force needed to produce a given acceleration

Question 6

What is Newton’s third law of motion

Answer 6

Whenever two objects interact, the forces they exert on each other are equal and opposite

Question 7

What is the stopping distance in terms of vehicles

Answer 7

The stopping distance is the total distance travelled from when the driver first spots the obstruction to when the car stops

Question 8

What is the thinking distance

Answer 8

The distance travelled by the car during the driver reaction time

Question 9

What is the reaction time

Answer 9

The time taken for the driver to spot the obstruction, make a decision and then move their foot to the brake

Question 10

What is the braking distance

Answer 10

The distance the car travels from when the driver applies the brakes to when the car stops

Question 11

What happens to the stopping distance if the speed of the vehicle increases

Answer 11

The greater the speed of the vehicle, the greater the stopping distance (if same braking force is applied)

Question 12

What factors can make a driver have a longer reaction time

Answer 12

• tiredness
• alcohol
• drugs
• distractions

Question 13

What happens to the thinking distance if the reaction time is greater

Answer 13

The longer the reaction time, the longer the thinking distance

Question 14

What factors increase the braking distance

Answer 14

• wet or icy conditions
• worn tires
• worn brakes
• mass in vehicle

Question 15

What is the overall stopping distance

Answer 15

Thinking distance + braking distance

Question 16

What happens to the braking force the greater the speed

Answer 16

The greater the speed, the greater the braking force needed to stop the car in a certain distance

Question 17

What will a large braking force cause

Answer 17

It will cause the car to decelerate rapidly

Question 18

What would happen if the brakes overheat

Answer 18

The driver could lose control of the vehicle

Question 19

How to calculate the force needed to decelerate

Answer 19

Force (n) = mass (kg) x acceleration (m/s squared)

Question 20

Momentum

Answer 20

• All moving objects have momentum

- if an object is not moving, its momentum is zero (no momentum)

Question 21

Momentum equation

Answer 21

Momentum (kg m/s) = mass (kg) x velocity (m/s)

Question 22

What happens in a closed system (conservation of momentum)

Answer 22

In a closed system, the total momentum before an event is equal to the total momentum after an event (momentum has been conserved)