How Fast Does Howard Fly from the Cannon?

[leggomymeggo]

The amazing 'Howard the Human Projectile' is fired straight forward from a 300 kg circus cannon during a recent Ringling Bros. Barnum and Baily performance in La Plata. Howard has a mass of 75 kg and the cannon recoils with a velocity of 2.5 m/s, at what initial velocity does Howard leave the cannon?




a. 2.5 m/s

b. 10 m/s

c. 25 m/s

d. 187.5 m/s

I am completely stuck ):

 

[NobodySpecial]

momentum is conserved
the momentum of howard going forward = momentum of cannon going backwards

 

[Apphysicist]

Note that initially, the cannon+Howard have no velocity, and so zero momentum. So the sum of the momenta of the cannon and Howard afterward also has to equal zero, so that you conserve momentum (initial=final). Be sure to keep tabs on your directions (Howard moves opposite the direction of the cannon) because momentum is a vector (but you're dealing with one dimension, which simplifies it a bit).

 

[Raza]

If 300kg object moved backward at the rate of 2.5m/s, then how far did a 75kg object move back?

(2.5/75)*300