Solve for Man's Velocity on Ice After Throwing Book at 20 m/s

[terpsgirl]

Velocity question?? Need help..

An 80.0 kg man is standing on a frictionless ice surface when he throws a 4.00 kg book at 20.0 m/s. WIth what velocity does the man move across the ice?


Would I be using Mass= weight/gravity?

Astronaut weight = 80.0 kg
Astronaut v = ? m/s

Book weight= 4.00 kg
Book v= 20.0 m/s

 

[chroot]

Are you familiar with the conservation of linear momentum?

- Warren

 

[KnowledgeIsPower]

An 80.0 kg man is standing on a frictionless ice surface when he throws a 4.00 kg book at 20.0 m/s. WIth what velocity does the man move across the ice?


Would I be using Mass= weight/gravity?

Astronaut weight = 80.0 kg
Astronaut v = ? m/s

Book weight= 4.00 kg
Book v= 20.0 m/s

Apply the law of linear momentum.
Before the throw: Man mass = 80kg, velocity = 0, Book mass = 4kg, velocity = 0.
After the throw: Man mass = 80kg, velocity = V. Book mass = 4kg, velocity = 20.

M1U1 + M2U2 = M1V1 + M2V2
(80x0) + (4x0) = (80V) + (4x20)
0=80V + 80
80V = -80
V = -80/80
V= -1m/s.