Forces

Question 1

Force

Answer 1

A force can change the motion of an object (N)

Question 2

Newton

Answer 2

The unit of force (N)

Question 3

Resultant force

Answer 3

The single force that has the same effect as all the objects acting on an object

Question 4

Mass

Answer 4

The quantity of matter in an object - a measure of the difficulty of changing the motion of an object (kg)

Question 5

Stopping distance

Answer 5

Thinking distance + braking distance (m)

Question 6

Thinking distance

Answer 6

The distance travelled by the vehicle in the time it takes the driver to react

Question 7

Braking distance

Answer 7

The distance travelled by the vehicle during the time its brakes act

Question 8

Weight

Answer 8

The force of gravity on an object (N)

Question 9

Gravitational field strength (g)

Answer 9

The force of gravity on an object of mass 1 kg (N/kg)

Question 10

Drag force

Answer 10

A force opposing the motion of an object due to a fluid flowing past the object as it moves

Question 11

Terminal velocity

Answer 11

The velocity an object falling in a fluid reaches when the weight is equal to the drag force on it

Question 12

f=ma

Answer 12

force (N) = mass (kg) x acceleration (m/s^2)

Question 13

w=mg

Answer 13

weight (N) = mass (kg) x acceleration due to gravity (m/s^2)

Question 14

Elastic

Answer 14

A material able to regain its shape after being squashed or stretched

Question 15

Directly proportional

Answer 15

Shown by a graph if the line of best fit is a straight line through the origin

Question 16

Limit of proportionality

Answer 16

The limit for Hooke’s law applied to the extension of a stretched spring

Question 17

Hooke’s law

Answer 17

The extension of a spring is directly proportional to the force applied, provided its limit of proportionality is not exceeded

Question 18

f=ke

Answer 18

force (N) = spring constant of a spring (N/m) x extension of a spring (m)

Question 19

What can forces do?

Answer 19

A force can change the shape of an object or change its motion or state of rest

Question 20

What is the SI unit of force?

Answer 20

Newton (N)

Question 21

When two objects interact, what can we say about the forces acting?

Answer 21

The forces are always equal and opposite to each other

Question 22

What happens when the resultant force on an object is zero?

Answer 22

The object stays at rest or at constant velocity

Question 23

What happens when the resultant force on an object is not zero?

Answer 23

The velocity of the object will change

Question 24

How do we calculate the resultant force when an object is acted on by two forces acting along the same line?

Answer 24

The force is the their sum if the objects are acting in the same direction, and the difference if the forces act in opposite directions

Question 25

How does the acceleration of an object depend on the size of the resultant force?

Answer 25

The bigger the resultant force, the greater the acceleration

Question 26

What effect does the mass of the object have on its acceleration?

Answer 26

The greater the mass of the object, the smaller its acceleration for a given force

Question 27

What forces oppose the driving force of a car?

Answer 27

Friction and air resistance

Question 28

What does the stopping distance of a vehicle depend on?

Answer 28

The thinking distance and braking distance

Question 29

What factors can increase the thinking distance?

Answer 29

Tiredness, alcohol and drugs affect reaction times, and the faster the vehicle is traveling, the greater the thinking distance

Question 30

What factors can affect the braking distance?

Answer 30

The faster the vehicle is traveling, the further it must travel before it stops. Adverse road conditions (on wet or icy roads drivers have to brake with less force to avoid skidding) or a poorly maintained car increase the braking distance

Question 31

What is the difference between mass and weight

Answer 31

The weight of an object is the force of gravity on it, whereas its mass is the quantity of matter in it

Question 32

What can we say about the motion of a falling object acted on only by gravity?

Answer 32

It will accelerate at 9.8 m/s² (round to 10)

Question 33

How do we measure the extension of an object when it is stretched?

Answer 33

The extension is the difference between the length of the spring and the original length

Question 34

How does the extension of a spring vary with the force applied to it?

Answer 34

The extension of a spring is directly proportional to the force applied to it, provided the limit of proportionality is not exceeded

Question 35

What is the spring constant of a spring?

Answer 35

The spring constant of a spring is the force per unit extension needed to stretch it

Question 36

How can the fuel economy of road vehicles be improved?

Answer 36

Reducing the speed or fitting a wind deflector

Question 37

What is an average speed camera?

Answer 37

Average speed cameras are linked in pairs and the measure the average speed of a vehicle

Question 38

What is the point of anti-skid road surfaces?

Answer 38

They increase the friction between a car tyre and the road surface, thus reducing or even preventing altogether skids