Learning Objectives :Learning Objectives :

1.1. To recognise To recognise projectile-like projectile-like problemsproblems2.2. To check understanding via motion To check understanding via motion

graphsgraphs3.3. To set the scene for harder problemsTo set the scene for harder problems

Book References : Pages 128-129 & 122-123Book References : Pages 128-129 & 122-123

Projectile-like motion:Projectile-like motion:

During the last lesson we looked at the During the last lesson we looked at the motion of falling objects given a motion of falling objects given a horizontal projectionhorizontal projection

This can be used to consider the motion of any This can be used to consider the motion of any object which experiences:object which experiences:

A constant velocity in one direction and a A constant velocity in one direction and a constant acceleration in another.... For example:constant acceleration in another.... For example:

1.1.A ball rolling A ball rolling acrossacross an inclined plane an inclined plane2.2.Electron beam between charged platesElectron beam between charged plates

An example....An example....

A ball is projected horizontally at 0.52 msA ball is projected horizontally at 0.52 ms-1-1 across across the top of an inclined board which is 60cm wide the top of an inclined board which is 60cm wide (horizontally) and 120cm high (vertically in the (horizontally) and 120cm high (vertically in the direction of the incline). The ball reaches the direction of the incline). The ball reaches the bottom of the board in 0.9s. Calculate the bottom of the board in 0.9s. Calculate the following:following:

a)a)The distance travelled across the board The distance travelled across the board [0.468m][0.468m]

b)b)Its acceleration on the board Its acceleration on the board [2.96ms[2.96ms-2-2]]

c)c)Its speed at the bottom of the board Its speed at the bottom of the board [2.8ms[2.8ms-1-1]]

Motion graphs for projectile motion :

For example consider an object thrown upwards:

Dis

plac

emen

t

Time

Maximum height

Dis

tanc

e

Time

Maximum height

Motion graphs for projectile motion :

For example consider an object thrown upwards:

Dis

plac

emen

t

Time

Maximum height

Dis

tanc

e

Time

Maximum height

Vel

ocity

Time

Maximum height

Vel

ocity

Time

Maximum height

+u

-u

t=u/g

More challenging problems (a taster)

So far the most difficult scenario we’ve considered is purely horizontal projection under the influence of gravity....

What about firing something from a gun with an initial vertical velocity or using a golf club other than a putter?

Not required for our specification. But those taking Maths are likely to come across it in Mechanics 2