P2.1 Forces and their effects

Question 1

What happens when two objects interact?

Answer 1

The forces they exert on each other are equal and opposite

Question 2

What may a number of forces acting at a point be replaced by?

Answer 2

A single force that has the same affect on the motion as the original forces all acting together, this single force is called the resultant force

Question 3

What may a resultant force acting on an object cause?

Answer 3

A change in its state of rest or motion

Question 4

What happens if the resultant force acting on a stationary object is zero?

Answer 4

The object will remain stationary

Question 5

What happens if the resultant force acting on a stationary object is not zero?

Answer 5

The object will accelerate in the direction of the resultant force

Question 6

What happens if the resultant force acting on a moving object is zero?

Answer 6

The object will continue to move at the same speed and in the same direction

Question 7

What happens if the resultant force acting on a moving object is not zero?

Answer 7

The object will accelerate in the direction of the resultant force

Question 8

What is the acceleration of an object determined by?

Answer 8

The resultant force acting on the object and its mass

Question 9

What is the equation for resultant force and acceleration?

Answer 9

a = F/m or F = m x a

Question 10

What is the resultant force measured in?

Answer 10

Newtons, N

Question 11

What is the mass measured in?

Answer 11

Kilograms, Kg

Question 12

What is acceleration measured in?

Answer 12

Metres per second squared, m/s squared

Question 13

What does the gradient of a distance-time graph represent?

Answer 13

Speed

Question 14

How do you calculate speed on a distance-time graph?

Answer 14

vertical axis / horizontal axis (should be distance/time)

Question 15

What is the velocity of an object?

Answer 15

It’s speed in a given direction

Question 16

What is the equation for acceleration with velocity?

Answer 16

v - u
a = ——–
t

Question 17

What is velocity measured in?

Answer 17

m/s

Question 18

What does the v stand for?

Answer 18

Final velocity

Question 19

What does the u stand for?

Answer 19

Initial velocity

Question 20

What does the gradient on a velocity-time graph represent?

Answer 20

Acceleration

Question 21

How do you work out the acceleration from a velocity-time graph?

Answer 21

Vertical axis / horizontal axis

Question 22

How do you work out the distance from a velocity-time graph?

Answer 22

Work out the area beneath the line

Question 23

When a vehicle travels at a steady speed…

Answer 23

The resistive forces balance the driving force

Question 24

What are most resistive forces caused by?

Answer 24

Air resistance

Question 25

The greater the speed of a vehicle...

Answer 25

The greater the braking force needed to stop it in a certain distance

Question 26

The greater the speed of a vehicle...

Answer 26

The greater the stopping distance

Question 27

What is the stopping distance of a vehicle?

Answer 27

The sum of the distance the vehicle travels during the driver's reaction time (thinking distance) and the distance it travels under the braking force (braking distance)

Question 28

What can a driver's reaction time be affected by?

Answer 28

Tiredness, drugs, alcohol and sometimes distractions

Question 29

What happens when the brakes of a vehicle are applied?

Answer 29

The work done by the friction force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increase

Question 30

What can a vehicle's braking distance be affected by?

Answer 30

Adverse road and weather conditions and poor condition of the vehicle

Question 31

What do adverse road and weather conditions include?

Answer 31

Wet or icy conditions

Question 32

What does poor condition of the car entail?

Answer 32

Poor condition of the car's brakes or tyres

Question 33

The faster an object moves through a fluid...

Answer 33

The greater the frictional force that acts upon it

Question 34

What will an object travelling through a fluid initially do?

Answer 34

Accelerate due to the force of gravity

Question 35

What will happen eventually when an object is travelling through a fluid?

Answer 35

The resultant force will be zero and the object will move at its terminal velocity, a steady speed

Question 36

Why do parachutes reduce terminal velocity?

Answer 36

Because their large surface area increases air resistance

Question 37

How do you calculate the weight of an object?

Answer 37

W = m x g

Question 38

What does g stand for?

Answer 38

The gravitational field strength

Question 39

What is gravitational field strength measured in?

Answer 39

Newtons per kilogram, N/Kg

Question 40

What is the gravitational field strength on earth?

Answer 40

10N/Kg

Question 41

What is weight measured in?

Answer 41

Newtons, N

Question 42

What may a force acting upon an object cause?

Answer 42

A change of shape of the object

Question 43

What will a force being applied to an elastic object, such as a spring, result in?

Answer 43

The object stretching and storing elastic potential energy

Question 44

For an object that is able to recover its original shape, where is elastic potential energy stored?

Answer 44

In the object when work is done on the object to change its shape

Question 45

What is the extension of a plastic object directly proportional to?

Answer 45

The force applied, provided that the limit of proportionality is not exceeded

Question 46

What is the equation to work out the force with a spring and extension?

Answer 46

F = k x e

Question 47

What does k stand for?

Answer 47

The spring constant in newtons per metre, N/m

Question 48

What does the e stand for?

Answer 48

Extension in metres, m