Forces and Motion

Question 1

What is the unit for force?

Answer 1

Newtons (N)

Force is a vector quantity.

Question 2

Is mass a scalar or vector quantity?

Answer 2

Scalar

Mass is measured in kilograms (kg).

Question 3

What is the unit for time?

Answer 3

Seconds (s)

Time is a scalar quantity.

Question 4

What is the unit for distance?

Answer 4

Metres (m)

Distance is a scalar quantity.

Question 5

What type of quantity is speed?

scalar or vector?

Answer 5

Scalar

Speed is measured in metres per second (m/s).

Question 6

Is velocity a scalar or vector quantity?

Answer 6

Vector

Velocity is measured in metres per second (m/s).

Question 7

What type of quantity is acceleration?

scalar or vector?

Answer 7

Vector

Acceleration is measured in metres per second squared (m/s²).

Question 8

What is the formula for weight?

Answer 8

Weight = mass * gravitational field strength

Weight is a vector quantity measured in Newtons (N).

Question 9

What is the formula for average speed?

Answer 9

Average speed = distance travelled / time taken

Question 10

What is the formula for average velocity?

Answer 10

Average velocity = displacement / time taken

Question 11

What is the difference between distance and displacement?

Answer 11

Distance is how far you travelled; displacement is the straight-line distance from your starting to finishing point.

Displacement is a vector quantity.

Question 12

What is the formula for resultant force?

Answer 12

Resultant force = vector sum of all forces
Resultant force = mass x acceleration (F = ma)

Question 13

What is the formula for acceleration?

Answer 13

Acceleration = change in velocity / time taken

Question 14

What does a constant gradient on a distance-time graph indicate?

Answer 14

Constant speed

Question 15

What does a curving line on a distance-time graph indicate?

Answer 15

acceleration

Question 16

What does a steeper line on a distance-time graph indicate?

Answer 16

Greater speed

The gradient of the line represents speed.

Question 17

What happens if the gradient of a distance-time graph is negative?

Answer 17

The object is returning to the start point

Question 18

What is the formula for calculating the gradient of a line?

Answer 18

Gradient = rise / run

The rise is the change in y, and the run is the change in x.

Question 19

What does a curved line show on a velocity-time graph?

Answer 19

increasing/decreasing acceleration

Decreasing acceleration is STILL ACCELERATING, just more slowly

Question 20

What does a constant gradient in a velocity-time graph indicate?

Answer 20

Constant acceleration

Question 21

What does constant speed on a velocity-time graph look like?

Answer 21

A horizontal line above the time axis

Question 22

What is the gradient of a velocity-time graph?

Answer 22

acceleration

Question 23

What does a negative velocity indicate about the object’s direction?

Answer 23

The object has changed direction

Question 24

What does the area under the line in a velocity-time graph represent?

Answer 24

Displacement

Question 25

What happens when there is a negative gradient in a velocity-time graph?

Answer 25

The object is decelerating

Question 26

What are the variables in the standard equations of motion? | SUVAT equation

Answer 26

Displacement, initial velocity, final velocity, acceleration, time

Question 27

What does decreasing acceleration indicate about an object's motion?

Answer 27

The object's acceleration is reducing but it is still accelerating

Question 28

What is the relationship between weight and air resistance as speed increases?

Answer 28

As speed increases, air resistance increases too.

Question 29

What happens when air resistance almost equals weight?

Answer 29

The resultant force is zero and terminal velocity has been reached.

Question 30

What occurs when the parachute opens?

Answer 30

The resultant force is upwards, causing speed to slow down.

Question 31

What is terminal velocity?

Answer 31

The fastest speed an object can reach when falling through a fluid.

Question 32

What is the formula for stopping distance?

Answer 32

stopping distance = thinking distance + braking distance.

Question 33

Define 'reaction time'.

Answer 33

The time it takes between seeing something and reacting.

Question 34

What factors can increase stopping distance? (List at least three)

Answer 34

* speed the car is travelling * distractions (phone, alcohol, drugs) * tiredness * bad reaction time (old age) * condition of tyres * worn-down brakes * mass of vehicle * wet or icy roads.

Question 35

Fill in the blank: Thinking distance is the distance a car travels _______.

Answer 35

[while reacting].

Question 36

Fill in the blank: Braking distance is the distance a car travels _______.

Answer 36

[while braking].

Question 37

What happens to air resistance as terminal velocity is approached?

Answer 37

Air resistance increases but more slowly, almost matching weight.

Question 38

What is momentum?

Answer 38

The product of an object's mass and velocity, and it is a vector quantity.

Question 39

What is the unit for momentum?

Answer 39

Kilogram metres per second (kg m/s) and a direction.

Question 40

What is the formula for momentum?

Answer 40

mass x velocity ## Footnote In symbols, it can be expressed as p = mv.

Question 41

What happens when an external force acts on an object?

Answer 41

There will be a change in velocity.

Question 42

What is impulse?

Answer 42

Force x time taken. It is a vector.

Question 43

What are the units for impulse?

Answer 43

Units are Newton seconds (N s).

Question 44

What is the formula for impulse?

Answer 44

Impulse = force x time

Question 45

What does a resultant force acting on an object cause?

Answer 45

It will cause the object to accelerate in the direction of the force. ## Footnote This is true if the mass of the object doesn't change.

Question 46

How can you find the resultant force?

Answer 46

Change in momentum / time taken

Question 47

What is the relationship between impulse and momentum?

Answer 47

Impulse = change in momentum

Question 48

What does Newton's third law of motion state about object A + B when A exerts a force on B

Answer 48

If object A exerts a force on object B, then object B will exert an equal and opposite force on A.

Question 49

What does the principle of conservation of momentum state?

Answer 49

When two objects experience a force of equal magnitude for the same length of time and in opposite directions, they will have an equal and opposite momentum, and total momentum is constant.

Question 50

In a closed system, the total momentum before and after a collision must be ...

Answer 50

equal

Question 51

What must be reduced to zero to decrease fatalities in head-on collisions?

Answer 51

The momentum of the car and passengers

Question 52

If change in momentum is the same with or without a safety feature, then why is force=rate of change of momentum significant?

Answer 52

Increasing the time over which momentum changes decreases the force experienced, decreasing the risk of injury

Question 53

How do crumple zones contribute to safety in collisions?

Answer 53

Crumple zones increase time until the car stops

Question 54

What role do airbags play in a collision?

Answer 54

Airbags increase collision time for the passenger's head

Question 55

What are the two purposes of seat belts?

Answer 55

* Provide the resultant force needed to bring the passenger to rest with the car * Stretch slightly, increasing collision time

Question 56

What happens if you don't wear your seatbelt in a collision?

Answer 56

No resultant force will be added, and the passenger will continue moving forwards ## Footnote This follows Newton's first law of motion, where an object in motion stays in motion.

Question 57

What are the conditions for pairs of forces according to Newton's third law?

Answer 57

* Equal in size (magnitude) * Acting in opposite directions * Same type of force * Acting along the same line (axis) * Acting on different bodies