# Edexcel Physics Unit 1

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• Created by: natasha
• Created on: 06-03-13 09:44
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### Page 1

PHYSICS
1 ­ Motion

Describing motion

ms-1

A distance-time graph can make it easier to represent motion
A velocity (speed in a given direction) ­ time graph can show the instantaneous speed

DISTANCE-TIME: VELOCITY-TIME:

Shows distance from start Gradient shows acceleration
Curved line is acceleration Straight line is constant speed…

### Page 2

Acceleration is the rate of change of velocity with time, so it is also a vector. Acceleration
happens when there is:
A change in SPEED, or
A change in DIRECTION, or
A change in speed AND direction

If an objects speed is constant but its velocity is changing, we say…

### Page 3

Non-linear graphs (curved graphs) ­ make strips/rectangles under the graph, calculate the
area and add it up this is less accurate than a linear graph

Equations of motion

SUVAT
s = displacement (m)
u = initial velocity (ms-1)
v = final velocity (ms-1)
a = acceleration (ms-2)
t = time…

### Page 4

Eg. If someone is running along a moving walkway with a velocity of 2 ms -1 relative to the
walkway, but if the walkway has a velocity of -2 ms-1, the person will remain in the same
positive relative to the ground.

1.2 ­ Forces

Causes of motion

THE BALL…

### Page 5

diagram. A diagram which shows all the forces acting on a body in a certain situation is
called a FREE BODY DIAGRAM . This doesn't show forces acting on objects other than
the one being considered.

CENTRE OF GRAVITY ­ the weight of an object acting through a single point…

### Page 6

Newton's second law of motion

In an experiment, the acceleration can be measured for various values of the resultant
force acting on the trolley while its mass is kept constant. On a graph of acceleration
against resultant force, a straight line will show that ACCELERATION IS
PROPORTIONAL TO THE RESULTANT…

### Page 7

g= F/m g is Nkg-1
W = mg

Electrical scale ­ a piece of conducting metal is compressed or deformed by an objects
weight, changing its electrical resistance. It measures WEIGHT

A beam balance measures MASS as the FORCES have to be balanced

Newton's third law of motion

Forces come…

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RESOLVING FORCES

The bunting and rope pull on the pole as a
result of being pulled tight. The bunting
pulls horizontally to the left while the
bracing rope pulls down and to the right.

When you resolve the forces and work out
what components are acting vertically and
what are…

### Page 10

2.1 ­Fluid flow

Fluid ­ a substance that can flow ­ normally a gas or liquid, but some solids can sometimes
behave like this

Density

Fluid density is also
mass per unit volume

When an object is SUBMERGED in fluid, it feels an upward force caused by the fluid
pressure…

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Awesome

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Your notes are so great! Thank you so much for sharing :)

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These notes are great and easy to understand. Thank you very much.

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