Question

A moving object has a kinetic energy of 150 j and a momentum with a magnitude of 30.0 kg•m/s. determine the mass and speed of the object

Answer 1

To determine the answer to this item, we use two (2) equations.

Equation for kinetic energy:
   KE = 0.5 mv²

Equation for momentum:
  P = mv

From the second equation, we can deduced that,
  m = P/v
Substituting the known values from the given above,

  m = 30/v

Using this expression in the first equation,

  KE = 0.5 mv²;   150 = 0.5(30/v)(v²)

The value of v from the equation is 10 m/s. 

The mass is therefore calculated as such,
  m = 30/v = 30/10 = 3 kg

Hence, the answers are,

 Mass  = 3 kg
 Velocity = 10 m/s