Forces

Question 1

Scalar

Answer 1

A quantity that only has magnitude

Question 2

Vector

Answer 2

A quantity with both magnitude and direction

Question 3

How can a vector quantity be shown?

Answer 3

As an arrow
Length of arrow shows the magnitude
Arrow points in the associated direction

Question 4

What is a force?

Answer 4

A push or pull acting on an object due to an interaction with an object

Question 5

What two categories can all forces be split into?

Answer 5

Contact and non-contact

Question 6

Three examples of contact forces:

Answer 6

Friction
Air resistance
Tension

Question 7

Three examples of non-contact forces:

Answer 7

Gravitational forces
Electrostatic forces
Magnetic forces

Question 8

Is force vector or scalar?

Answer 8

Vector

Question 9

Three examples of vector quantities:

Answer 9

Velocity
Displacement
Force

Question 10

Three examples of scalar quantities:

Answer 10

Time
Mass
Distance
Speed

Question 11

What is weight?

Answer 11

The force that acts on an object due to gravity and the object’s mass

Question 12

What quantities does weight depend on?

Answer 12

The object’s mass
The gravitational field strength

Question 13

What unit is used for weight?

Answer 13

Newton (N)

Question 14

What is the unit used for gravitational field strength?

Answer 14

N/kg

Question 15

What is an objects centre of mass?

Answer 15

The single point where an object’s weight can be considered to act through

Question 16

What equipment can be used to measure an object’s weight?

Answer 16

A calibrated spring balance or Newton meter

Question 17

Resultant force

Answer 17

The single force that is equivalent to all the other forces acting on a given object

Question 18

What does it mean if a force is said to do work?

Answer 18

The force causes an object to be displaced through a distance

Question 19

What equation calculates work done?

Answer 19

Work done(J)=force(N) x distance(m)

Question 20

What occurs when work is done against frictional forces?

Answer 20

A rise in temperature of the object occurs
Kinetic energy is converted to heat

Question 21

What is the relationship between the force applied and the extension of an elastic object?

Answer 21

Directly proportional (provided that the limit of proportionality is not exceeded)

Question 22

What is inelastic deformation?

Answer 22

A deformation that leaves the object being permanently stretched
The object doesn’t return to it’s original shape when the force is removed

Question 23

What equation links force, spring constant and extension?

Answer 23

Force(N)=Spring constant(N/m) x Extension(m)

Question 24

What energy is stored in a spring when it’s stretched?

Answer 24

Elastic potential energy

Question 25

What can extension be replaced with in the equation for spring force?

Answer 25

Compression

Question 26

What is the typical value for the speed of sound?

Answer 26

330m/s

Question 27

What is the typical value for human walking speed?

Answer 27

1.5m/s

Question 28

What is the typical value for human running speed?

Answer 28

3m/s

Question 29

What is the typical value for human cycling speed?

Answer 29

6m/s

Question 30

What equation links distance speed and time?

Answer 30

Distance(m)=Speed(m/s) x Time(s)

Question 31

Why can an object travelling at a constant speed in a circle not have a constant velocity?

Answer 31

Speed is scalar Velocity is a vector meaning it can only be constant if the direction is constant In circular motion the direction is constantly changing

Question 32

How can speed be calculated from a distance-time graph?

Answer 32

Gradient of the graph

Question 33

What must be done to calculate speed at a given time from a distance-time graph for an accelerating object?

Answer 33

Drawing a tangent to the curve at the required time Calculating the gradient of the tangent

Question 34

What is the equation for the average acceleration of an object?

Answer 34

Acceleration(m/s2)=(Change in velocity(m/s)) / (Time taken(s))

Question 35

How can distance travelled by an object be calculated from a velocity-time graph?

Answer 35

Area under the graph

Question 36

Approx value for the acceleration of an object in free fall under gravity near the Earth's surface?

Answer 36

9.8m/s^2

Question 37

What can be said about the resultant force acting on an object when it's falling at a terminal velocity?

Answer 37

Resultant force is zero Constant speed so it isn't accelerating

Question 38

Newton's first law for a stationary object:

Answer 38

If the resultant force on a stationary object is zero, the object will remain at rest

Question 39

Newton's first law for a moving object:

Answer 39

If the resultant force on a moving object is zero, the object will remain at constant velocity

Question 40

What is inertia?

Answer 40

The tendency of an object to continue in its state of rest or uniform motion

Question 41

Newton's second law:

Answer 41

An object's acceleration is directly proportional to the resultant force acting on it and inversely proportional to its mass

Question 42

Equation for Newton's second law:

Answer 42

Resultant force(F)=Mass(m) x Acceleration(a)

Question 43

What is inertial mass?

Answer 43

A measure of how difficult it is to change a given object's velocity The ratio of force over acceleration

Question 44

Newton's third law:

Answer 44

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

Question 45

What is the stopping distance of a vehicle equal to?

Answer 45

Sum of thinking distance and braking distance

Question 46

Typical range of values for human reaction time:

Answer 46

0.2-0.9 seconds

Question 47

Three factors that can affect a driver's reaction time:

Answer 47

Tiredness Drugs Alcohol

Question 48

Two factors that may affect braking distance:

Answer 48

Wet/icy road conditions Poor tyre/brake conditions

Question 49

Equation for momentum:

Answer 49

Momentum=Mass x Velocity

Question 50

What unit is used for momentum?

Answer 50

Kg m/s

Question 51

State an equation linking change in momentum, force and time:

Answer 51

Change in momentum=Force x Time