9.1 - linear motion

movement of a body in a straight or curved line, where all parts move the same distance, in the same direction over the same time

 a water skier on a flat lake being pulled at a constant speed will travel in linear motion as all parts of their body will travel the same direction over the same distance per unit of time

direct force being applied directly to the body’s centre of mass

a force applied through centre of mass resulting in linear motion

the point at which the body is balanced in all directions

it is the point at which weight appears to act

the total length covered from start to finish

metres → m

e.g

• distance covered in an 100m sprint is 100m

the shortest straight line route between the start and finish

e.g

• the displacement of an 100m sprint is 100m

• 2 lengths of a swimming pool displacement is 0m as start and finish in the same place

the rate if change in distance

m/s → metres per second

calculated using:

• speed = distance / time

the rate of change in displacement

m/s → metres per second

calculated using:

• velocity = displacement / time taken

rate of change in velocity

m/s/s → metres per second squared

acceleration = (final vel - initial vel)/ time taken

• pos = acceleration

• negative = deceleration

a visual representation of distance travelled plotted against time taken

a visual representation of the speed of motion plotted against the time taken

gradient = acceleration of a body

• pos grad = acceleration

• straight = constant speed

• neg grad = deceleration

area underneath = distance travelled

a visual representation of the velocity of motion plotted against the time taken 

gradient = acceleration of a body at rest or travelling at a constant velocity

A 

• X axis = 0 

  • Rest or stationary position 

A-B 

• Upward curve shows an increase in velocity 

• Acceleration 

B-C 

• No change in velocity per unit of time 

• Uniform velocity = velocity is constant at this point

A-B 

• Acceleration 

• Player A applies a force to accelerate the ball towards player B 

B-C 

• Deceleration 

• Player b cushions the ball to decelerate it to a resting position at C 

C-D 

• Rest 

• Player b controls the ball and prepares to return the pass 

D-E 

• Acceleration followed by deceleration in the opposite direction 

• Player b applies the force to the ball, accelerating it back to player A ,who cushions the ball so decelerating it to rest