3.1 Motion Flashcards Preview

AS Physics > 3.1 Motion > Flashcards

Flashcards in 3.1 Motion Deck (28):
1

Instantaneous Speed

The speed at a certain time

2

Displacement

A vector quantity that represents how far an object has travelled from its starting point in a given direction

3

Average Speed

Distance / Time

4

Average Velocity

Displacement / Time

5

Distance

A scalar quantity that shows how far something travelled along a certain route

6

Velocity

A vector quantity that shows rate of change of displacement

7

Acceleration

A vector quantity, the rate of change of velocity

8

Gradient of displacement-time graph

Velocity

9

Gradient of velocity-time graph

Acceleration

10

Area under velocity-time graph

Displacement

11

The 4 SUVAT equations

v = u + at
s = 0.5(u + v)t
s = ut + 0.5at^2
v^2 = u^2 + 2as
(s = vt - 0.5at^2)

12

value of g

9.81

13

Acceleration of a body in free fall

-g

14

Is horizontal velocity independent of vertical

yes

15

The two types of approaches for measuring g

Direct e.g. timing a falling ball
Indirect e.g. timing a pendulum

16

Describe the experiment to measure g (trapdoor)

- Set up a steel ball supported by an electromagnet
- Turn of current so ball is released and clock started
- When ball hits trap door a connection is broken and timer is stopped
- We now have u, s, t and want to find a so we can rearrange a SUVAT
- Can plot a graph with different values of s (and t)

17

Potential sources of error for g trapdoor experiment (3)

- Electromagnet current too high can cause delay
- If distance is too large air resistance might have a noticeable effect
- Measurement of distance

18

Experiment to measure g (light gates)

- A piece of card is dropped from a certain height above a light gate
- Light gate and data logger calculate v, u = 0, s = measured so a can be calculated
- A graph of v^2 against s can be plotted with the gradient being 2g

19

Assumptions made by light gate g experiment

The cards velocity is constant as it travels through the gate

20

Thinking distance

Distance a car travels between driver seeing hazard and applying brakes

21

Braking Distance

Distance between applying brakes and coming to rest

22

Stopping distance

thinking distance + braking distance

23

Factors that increase thinking distance (5)

- high speed
- tiredness
- alcohol / drugs
- Distractions
- Age

24

Factors that increase braking distance (5)

- high speed
- poor road conditions
- poor brake conditions
- poor tyre conditions
- mass of car

25

Equation for thinking distance

reaction time * speed

26

Relationship between braking distance and speed

squared

27

Why is braking distance proportional to speed squared

Because brakes constantly do work against the car, and the total energy is 0.5mv^2

28

Equipment used to investigate motion and collisions of objects

- Trolleys, light gates, data loggers
- Video recording and analysing frame by frame