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Flashcards in Physics Deck (135)
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1

What happens when two objects interact

The forces they exert on each other are equal and opposite

2

What is a resultant force

When a number of forces acting at a point are replaced by a single force that has the same effect on the motion as the original forces all acting together

3

What can a resultant force acting on an object cause

A change in its state of rest or motion

4

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

The object will remain stationary

5

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

The object will accelerate in the direction of the resultant force

6

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

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

7

What is the acceleration of an object determined by

The resultant force acting on the object and the mass of the object

8

What does the gradient of a distance-time graph represent

Speed

9

What is the velocity of an object

Its speed in a given direction

10

What does the gradient of a velocity-time graph represent

Acceleration

11

What happens when a vehicle travels at a steady speed

The resistive forces balance the driving force

12

The greater the speed of a vehicle ...

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

13

What are most resistive forces caused by

Air resistance

14

What is the stopping distance of a vehicle a 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)

15

What can a drivers reaction time be affected by

Tiredness
Drugs
Alcohol

16

What may affect driver's ability to react

Distractions

17

What happens when the brakes of a vehicle are applied

Work done by the friction force between the brakes and the wheel reduces kinetic energy of the vehicle and the temperature of the brakes increases

18

What can a vehicles braking distance be affected by

Adverse road and weather conditions (wet and icy) and poor condition of the vehicle

19

The faster an object moves through a fluid ...

... The greater the frictional force that acts on it

20

Why will an object falling through a fluid initially accelerate

The force of gravity. But eventually the resultant force will be zero and the object will move at its terminal velocity (steady speed)

21

What is the equation to calculate the weight of an object using the force exerted on it by a gravitational force

W = M * G

W = weight in newtons, N
M = mass in kg
G = gravitational field strength in newtons per kilogram, N/kg

22

What may a force acting on an object cause

A change in shape of the object

23

What will a force applied to an elastic object (e.g. a spring) result in

Stretching and storing elastic potential energy

24

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

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

25

What is the extension of an elastic object directly proportional to

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

26

When is work done

When a force causes an object to move through a distance

27

How are work done, force and distance related by

The equation
W = F * D

W - work done in joules, J
F - force applied in newtons, N
D - distance moved in the direction of the force in metres, m

28

What is transferred when work is done

Energy

29

What is power

The work done or energy transferred in a given time
P = E/T

P - power in watts, W
E - energy transferred in joules, J
T - time taken in seconds, s

30

What is gravitational potential energy

The energy that an object has by virtue of its position in a gravitational field
Ep = m * g * h

Ep - change in gravitational potential energy in joules
M - mass in kg
G - gravitational field strength in newtons per kilogram, N/kg
H - change in height in metres, m