P9 - Motion

Question 1

Acceleration definition

Answer 1

Change of velocity per second (speeding up)

Question 2

Deceleration meaning

Answer 2

Change of velocity per second when an object slows down

Question 3

Displacement meaning

Answer 3

Distance in a given direction

Question 4

Gradient (of a straight line graph)

Answer 4

• change of the quantity plotted on the y axis divided by the change of the quantity plotted on the x axis

Question 5

Tangent meaning

Answer 5

• straight drawn to touch a point on a curve so it has the same gradient as the curve at that point

Question 6

Velocity definition

Answer 6

• speed in a give direction

Question 7

Velocity definition

Answer 7

Distance (spacium) / time

Question 8

Acceleration formula

Answer 8

a (m/s squared) = change in velocity / time

Question 9

Circular motion

Answer 9

• objects moving at constant speed in a circle are actually accelerating
• while speed is constant, the direction is continuously changing, due to a force towards the centre, therefore the velocity is changing

Question 10

When can can circular motion be seen?

Answer 10

When a ball is travelling in a circle then released. The ball will travel in a straight line at 90 degrees from its original position/force

Question 11

Velocity time graphs

Answer 11

Constant positive gradient = constant acceleration
Constant negative gradient = constant deceleration
Flat sections = velocity is constant
Gets steeper = gradient is increasing = acceleration is increasing
Gradient = change in velocity / time = acceleration

Question 12

How to find the distance travelled on a velocity time graph

Answer 12

Area of a triangle + area of a rectangle

To find the area under the curve, add up grid squares and combine squares if in halves

Question 13

What is terminal velocity?

Answer 13

When the drag is equal to the weight, so there is no resultant force
Forces are equal and opposite

Question 14

Describe the stages of terminal velocity

Answer 14

1. At the moment of leaving the plane, the person is accelerating and there is no/little drag, only weight force
2. Once they’ve left plane and their accelerating - drag increases but weight force is still greater than drag
3. Terminal velocity is when the drag = weight so no resultant force - constant speed
4. Just after opening the parachute, drag is more than weight force so they are decelerating
5. Parachute is slowing the person down, and velocity decreases so drag is equal to weight again and they reach terminal velocity.