Year 11 Physics - Motion and Forces

what is the centre of mass

a simple object located at a single point, known as an objects balance point

what does position mean

an objects location at a point in time, with respect to the origin

how is distance different to displacement

distance is only how far something has gone in total, but displacement is a change in position

what is the difference between instanteous speed and average speed

instantaneous is at a single point in time and average is over a period of time

how do you read instantaneous velocity of a position time graph

find the gradient of the tangent to the line at the point of interest

how do you find the average velocity on a position time graph

find the gradient of the chord between the two points in time

hwo do you find displacement on a velocity time graph

find the area under the curve

what does the gradient on a velocity time graph represent

average acceleration is the gradient of a chord

instantaneous acceleration is the gradient of a tangent

does mass affect how quickly an object falls

no

what is newtons first law

an object will remain at rest or continue with uniform velocity unless acted upon by an external resultant force

how do you draw a free body diagram

use a circle to represent the body

draw arrows from the circle outwards to show forces

up is lift, down is weight

side to side is drag and thrust (direction depends on situation)

what is newtons 2nd law of motion

the rate of chage of an objects linear momentum is directly proportional to the resultant external force. change in momentum takes place in the direction of the force

what is newtons 3rd law of motion

if body A exerts a force on body B, body B will exert and equal but opposite force on body A

describe an elastic collision

a collision in which kinetic energy is conserved and no energy is transferred to surrounds

describe an inelastic collision

a collision in which kinetic energy is not conserved. Energy is transferred to surrounds

what is an explosion

when the total momentum before will equal the total momentum after

but in explosions the total momentum before is zero

what is impulse

a change in momentum over time