Forces and Motion

Question 1

Unit of mass

Answer 1

Kilograms (kg)

Question 2

Unit of distance

Answer 2

Meters (m)

Question 3

Unit of speed

Answer 3

Metres/ seconds (m/s)

Question 4

Unit of acceleration

Answer 4

Metres/ seconds^2 (m/s^2)

Question 5

Unit of force

Answer 5

Newton (N)

Question 6

Unit of time

Answer 6

Seconds (s)

Question 7

Unit of Gravitational Field Strength (GFS)

Answer 7

Newtons/ kilogram (N/kg)

Question 8

Unit of momentum

Answer 8

Kilogram metres/ second (kg m/s)

Question 9

How to calculate the speed from a distance-time graph?

Answer 9

Find the gradient =
Change in y / Change in x

Question 10

What is the equation for Speed?

Answer 10

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

Question 11

What is the equation for Acceleration?

Answer 11

Acceleration (m/s^2) = Change in Velocity (m/s) / Time taken (s)

Question 12

How do you calculate the distance moved from a velocity-time graph?

Answer 12

Calculate the area under the graph

Question 13

How to calculate acceleration in a velocity-time graph?

Answer 13

Find the gradient =
Change in y / Change in x

Question 14

How to calculate Final Speed using final speed, initial speed, acceleration and distance moved?

Answer 14

v^2 = u^2 + 2as
(final speed)^2 = (initial speed)^2 + (2 x acceleration x distance moved)

Question 15

What is a scalar quantity?

Answer 15

A quantity that only has magnitude (eg. mass, kg)

Question 16

What is a vector quantity?

Answer 16

A quantity that has direction and magnitude (eg. force, velocity)

Question 17

What is a resultant force?

Answer 17

The sum of the total forces acting on an object.

Question 18

What is the equation that links Force, Mass and Acceleration?

Answer 18

F = ma

F = Force (N)
m = Mass (kg)
a = Acceleration (m/s^2)

Question 19

What is the equation that links weight, mass and Gravitational Field Strength?

Answer 19

W = mg

W = Weight (N)
m = Mass (kg)
g = Gravitational Field Strength (N/kg)

Question 20

What is the equation for stopping distance?

Answer 20

Stopping Distance = Thinking distance + Braking distance

Question 21

What are some factors affecting the stopping distance?

Answer 21

• Speed
• Mass
• Incline of road
• Impairment due to alcohol/drugs
• Condition of braking system
• Condition of road

Question 22

What is terminal velocity?

Answer 22

When the force of Weight downwards is the same as air resistance upwards and so the object moves at a constant velocity, with no overall force.

Question 23

What is the Hooke’s Law equation?

Answer 23

F = ke

F = Force (N)
k = Spring constant (N/M)
e = Extension (m)

Question 24

What is Hooke’s Law

Answer 24

Hooke’s Law states that the extension of a spring is directly proportional to the applied force, up to the limit of proportionality.

Question 25

What is an elastic?

Answer 25

A material that returns to its original shape after the forces causing deformation have been removed.

Question 26

What is the momentum equation?

Answer 26

p = m x v p = Momentum (kg m/s) m = Mass (kg) v = Velocity (m/s)

Question 27

Describe using the idea of momentum how airbags work as a safety feature?

Answer 27

- Airbags inflate quickly during a crash, preventing a passenger's head from hitting hard objects. - Increases the amount of time it takes for the momentum of the person's head to reach 0, reducing the rate of change. - F = mv-mu/t, so increasing t reduces F.

Question 28

Describe using the idea of momentum how seatbelts work as a safety feature?

Answer 28

- They prevent someone being thrown out of a car during a crash. - Seatbelts can stretch slightly, increasing the time taken for a person's body to stop moving, reducing the rate of change of momentum. - Since F = ma, reducing, a reduces F.

Question 29

Describe using the idea of momentum how crumple zones work as a safety feature?

Answer 29

- Crumple zones are areas of a vehicle that are designed to give way during a crash. - By doing so, they increase the time taken for the car to come to a stop, decreasing the rate of change. - Since F = ma, decreasing a decreases F.

Question 30

What is The Principle of the Conservation of Momentum

Answer 30

Momentum before = Momentum after

Question 31

What is the equation that links Force, Change in momentum and time taken.

Answer 31

F = (mv - mu) / t F = Force (N) mv = Final momentum (kg m/s) mu = Initial momentum (kg m/s) t = Time (s)

Question 32

What is Newton's First Law

Answer 32

An object will remain stationary or travel at constant velocity unless an external resultant force is applied.

Question 33

What is Newton's Second Law?

Answer 33

The acceleration of an object is directly proportional to the resultant force applied to the object. F = ma Also: F = (mv - mu) / t Force is the rate of change of momentum

Question 34

What is Newton's Third Law?

Answer 34

If Object A imparts a force on Object B, Object B imparts an equal and opposite force on Object A.

Question 35

What is the equation for Moments?

Answer 35

M = fd M = Moment (Nm) f = Force (N) d = Perpendicular distance to pivot (m)

Question 36

Explain this practical: Investigate how extension varies with applied force for helical springs, metal wires and rubber bands.

Answer 36

Set up a clamp with a weighted stand and a spring with hanging masses Measure length of spring when no load is applied Apply one mass and measure length of spring when it comes to a rest Repeat this and plot a graph of force vs total extension

Question 37

How does the weight of body acts with gravity?

Answer 37

It acts through its centre of gravity

Question 38

Explain the direction and how weight works as a force:

Answer 38

The result of your own mass being pulled down by a gravitational field Downwards

Question 39

Explain the direction and how driving force/ thrust works as a force:

Answer 39

A force that moves a mechanical object Fowards

Question 40

Explain the direction and how resistive forces works as a force:

Answer 40

Name given to all forces that try to slow down an object Backwards

Question 41

Explain the direction and how air resistance works as a force:

Answer 41

A force from air that slows down moving objects Backwards

Question 42

Explain the direction and how braking force works as a force:

Answer 42

A force deliberately applied to slow down a mechanical object Backwards

Question 42

Explain the direction and how friction works as a force:

Answer 42

Force from solids rubbing together (slows object and produces heat) Backwards

Question 43

Explain the direction and how upthrust works as a force:

Answer 43

A force from a fluid which helps keep planes in air Upwards

Question 43

Explain the direction and how reaction force works as a force:

Answer 43

A force pushing away from and object at 90°, reacting to the force pushing against it Away from surface

Question 44

Explain the direction and how electrostatic force works as a force:

Answer 44

A force between electrically charged objects Towards/ away from electric charge

Question 44

Explain the direction and how gravitational force works as a force:

Answer 44

An attractive force between any two masses arising from a gravitational field between any two masses

Question 45

Explain the direction and how magnetic force works as a force:

Answer 45

A force coming from a magnetic field Towards/ away from magnet

Question 46

Explain the direction and how tension works as a force:

Answer 46

A pull force acting in a rope, spring or piece of spring Along the object, away from object acting on it