5 points The figure below shows two people ice-skating. Person A collides with
person B. After the collision they move together with the same velocity.
Calculate the mass, m, of person B.

Before collision
After collision
Person A
mass = 60 kg
Person B
mass, m
Person A and person B
moving off together
Speed of
Person A -
5.5 m/s
Speed of
Person B -
2.0 m/s
Speed of Person A and
Person B = 4.0 m/s

mB = 45 kg

Explanation:

Using conservation of linear momentum,

mAvA + mbvB = (mA + mB)v

(60 kg)(5.5 m/s) + (2.0 m/s)mB = (60 kg + mB)(4.0 m/s)

(330) + 2mB = 240 + 4mB

2mB = 90

mB = 45 kg

electrical potential energy =0.072 j

explanation:

electrical potential energy is given by

u= q δv

q= charge=6 c

δv= potential difference and is given by

δv= e d

e= electric field

d= distance=5 mm=0.005 m

δv=2.4 (0.005)=0.012 v

now electric potential energy= u= q δv

u=6 (0.012)

u=0.072 j