# Projectile Motion Question (1 Viewer)

#### teeah

##### Member
Hey just wondering if someone could give this a go:

A 30kg object, A, was fired from a cannon in projectile motion. When the projectile was at its maximum height of 25m, its speed was 20ms^-1
An identical object, B was attached to a mechanical arm and moved at a constant speed of 20ms^-1 in a vertical half circle. The length of the arm was 25m. Ignore air resistance.
a) Calculate the force acting on object A at its maximum height.
b) Calculate the time it would take object A to reach the ground from its position of maximum height.
c) Describe and compare the vertical forces acting on objects A and B at their maximum heights. #### Fizzy_Cyst

##### Well-Known Member
a) Force due to gravity (Weight = mass * gravity)

b) I dont have a calculator at my disposal atm -- but using the formula delta_Y = Uyt + 1/2ayt^2 -- Uy = 0 (y-comp at max height = 0) -- t =sqrt(2*delta_Y/a) = approx 1.6s

c) A - gravity, what is it provided by? (give amount ?294? and direction) B - Centripetal force, what is it provided by? (give amount ?480? and direction) then express these forces as a ratio