physics word problem.PLEASE HELP !!!!!!?

Question

A moving object has a kinetic energy of 182 J and a momentum with magnitude of 28.2 kg·m/s.
(a) Determine the mass of the object.
(b) Determine the speed of the object.

Answer 1

Since kinetic energy is
Ke= 0.5mV^2 and momentum is
p=mv

we can express mass as
m=2Ke/V^2

and velocity as
v=p/m
so substituting expression for m we have
v=p/[2Ke/V^2]
1=pV/2Ke
V= 2Ke/p

also mas m is m=p/v

now we can find in reverse to the sequence asked
a) m=p/v=28.2/12.9=2.18 kg
b)V=2Ke/p=2x182/28.2=12.9 m/s

Answer 2

This is just a tricky way of setting up 2 simultaneous equations.

A Joule is also kg*(m/s)^2, so set them up like this:

1/2(M)(V^2) = 182 kg*(m/s)^2
M*V = 28.2 kg*m/s

Now substitute and solve. The second equation tells you that V = 28.2/M; put that into the first equation:

1/2(M)((28.2/M)^2) = 182

Solve for M, then substitute that value into the second equation and solve for V.

Answer 3

You know the energy E and the momentum p:

p^2/2m = E so m = p^2/2E
p = mv so v = p/m = p/(p^2/2E ) = 2E/p