Motion, Force And Energy Flashcards Preview

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Flashcards in Motion, Force And Energy Deck (32):
1

vector

Vector quantities have a magnitude and a direction

2

Scalar

Have quantities and no direction

3

Speed and velocity

Both measure how fast your going
Speed is scalar
Velocity is a vector
Means velocity can change if speed is staying the same

4

D = s x t

Distance = speed x time

5

Scalar quantaties

-Speed
-Distance
-Mass
-energy

6

Vector quantatities

-Force
-Velocity
-Displacement
-Weight
-Acceleration
-Momentum

7

Distance time graph

-The gradient represents the speed; the steeper the line the faster the speed

8

Velocity time graph

-Horizontal line= constant velocity
-Upwards sloping line = acceleration
-Downwards sloping line = deceleration
-Total distance travelled is shown by the area under the graph

9

a = v-u/t

acceleration (metre per second squared, m/s2) = change in
velocity (metre per second, m/s) ÷ time taken (second, s)

10

constant acceleration

uniform acceleration

11

v − u = 2× a× x

(final velocity)2 ((metre/second)2, (m/s)2) – (initial velocity)2
((metre/second)2, (m/s)2) = 2 × acceleration (metre per
second squared, m/s2) × distance (metre, m)

12

Typical speeds

-walking = 1.4m/s
-running = 3m/s
-Cycling = 5.5m/s
-cars in built up area = 13m/s

13

Equipment for measuring speed

light gates

14

Newton's first law of motion

An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force

15

If a stationary object experiences a resultant force of not zero

It will accelerate in the direction of the resultant force

16

If a moving object experiences a resultant force of not zero

It will accelerate in the direction of the resultant force

17

F = m× a

force (newton, N) = mass (kilogram, kg) × acceleration
(metre per second squared, m/s2)

18

W = m× g

weight (newton, N) = mass (kilogram, kg) × gravitational field
strength (newton per kilogram, N/kg)

19

Circular motion

Objects travelling in a circular motion are prevented from moving off in a straight line by centripetal force. This resultant force pulls objects toward the centre of the circle, continually changing the direction that an object is travelling in to keep it in circular motion.

20

Inertia

Inertia is the tendency for motion to remain unchanged.

21

Inertial mass

An object's inertia mass measures how difficult it is to change the velocity of an object
m = f/a

22

Newton's third law is:

For every action, there is an equal and opposite reaction.

23

What is the momentum of a stationary object?

zero

24

p = m × v

p is the momentum in kilograms metres per second, kg m/s
m is the mass in kilograms, kg
v is the velocity in m/s

25

Conservation of momentum

The total momentum of an object before an event is equal to the total momentum after the event

26

When does momentum change?

The momentum of an object can change if:
The object speeds up or slows down
The object changes direction

27

F = mv - mu / t

Force (newton, N) = change in momentum (kilogram
metre per second, kg m/s) ÷ time (second, s)

28

Stopping distance

Stopping distance of a vehicle is made up of the
sum of the thinking distance and the braking distance

29

Factors affecting the thinking distance

-Reaction time: increased by tiredness, drugs, alcohol and distractions
-Speed: the faster you're going the further your travel during reaction time

30

Factors affecting the stopping distance

-Speed: faster you're going longer it take to stop
-Mass of car: heavy wont stop as fast as empty car
-Wet or icy conditions
-Worn brakes/ Worn tyres

31

Large decelerations

Large decelerations can cause serious injury as it requires a larger force

32

Braking

To stop a car from moving we need to apply a force to transfer its kinetic energy into other forms - such as heat. This is what brakes do - they apply a force in the opposite direction to the motion of the car. This causes deceleration and eventually the car stops.