1.20 to 1.24 Plenary answers

Physics for You p.147 Q6

6.

Consider initial momentum

 

Man   

p = m x v

p = 80 x 0

p = 0kgm/s

 

Bullet  

p = m x v

p = 0.02 x 400

p = 8kgm/s     

 

total initial momentum = 8+0 = 8kgm/s   

 

Principle of Conservation of Momentum tells us:

total initial momentum = total final momentum

                               Σp_i = Σp_f

 

so total final momentum = 8kgm/s

 

Consider final momentum

 

Σp_f = p_bullet + p_man

8 = 0 + p_man

p_man = 8kgm/s

 

Man

p = m x v

8 = 80 x v

v = 0.1m/s

 

·         Considerably less dramatic than Hollywood!

Momentum and Impulse Plenary (Gapfill) - PFY.ppt Download this file