Physics 2 Useful Revision Notes
Chapter 1 Motion
Construction and uses of distance time graphs-
we can use these graphs to help us describe the motion of a body. a distance time graph shows that distance of a body from the starting point (y-axis) against time taken (x-axis). Look at the above example.
The slope on the line of a distance time graph represents the speed. the steeper the slope the greater the speed. The speed of a body is the distance traveled each second. we can calculate the speed of the body using the following equation:
Speed= Distance traveled/ Time taken Speed is measured in (M/S)
Construction and uses of velocity- time graphs
The velocity of a body is its speed in a given direction. if the body changes direction it changes velocity, even if its speed stays the same. if the velocity of a body changes we say that it accelerates. we can calculate acceleration by the following equation:
Acceleration= Change in speed/ time take for the change
Acceleration is measured in (m/s2)
if the value calculate for acceleration is negative, the body is deceleration- slowing down. look at the graph below showing the directions represented.
- the slope of the line on a velocity time graph represents acceleration.
- the steeper the slope the greater the acceleration.
- if the slope is negative, the body is decelerating.
- the area under the line on a time velocity graph represents the distance traveled in a given time.
- the bigger the area the greater the distance traveled.
Chapter 2 Speeding up and slowing down
Weight= Mass x Gravitational Field Strength
Forces: forces are measured in newtons (N). objects always exert equal and opposite forces on each other. if object A exerts a force on object B. object B exerts an equal opposite force on object A. these are sometimes called 'action and reaction' forces.
if a car hits a barrier it exerts a force on the barrier. the barrier exerts a force on the car that is equal in size and in the opposite direction. if you place a book on a table the weight of the book will act vertically downwards on the table. the table will exert an equal and opposite reaction force upwards on the book.
When a car is being driven forwards there is a force from the Tyre on the ground pushing backwards. there is an equal opposite force from the ground on the Tyre which pushes the car forwards.
What is resultant force?
most objects has more than one force acting on them. the resultant force is the singe force that would have the same effect on the as all the original forces acting together. when the resultant force on an object is zero:
- if the object is at rest it will stay at rest