Question

The momentum of a falling rock is found to be 200 kg m/s. What is the mass of the rock if it falls with a velocity of 5.0 m/s

Answer 1

`\boxed {\boxed {\sf 40 \ kilograms}}`

Step-by-step explanation:

Momentum is the product of velocity and mass. The formula is:

`p=m*v`

We know the rock is falling. Its momentum is 200 kilograms meters per second and its velocity is 5 meters per second. Substitute the values into the formula.

`200 \ kg \ m/s = m * 5.0 \ m/s`

We are solving for m, the mass. We must isolate the variable. It is being multiplied by 5 meters per second. The inverse of multiplication is division, so we divided both sides by 5.0 m/s.

`(200 \ kg \ m/s)/(5.0 \ m/s)=( m* 5.0 \ m/s )/(5.0 \ m/s)`

`(200 \ kg \ m/s)/(5.0 \ m/s)=m`

The units of meters per second (m/s) cancel.

`(200 \ kg)/(5.0 ) =m`

`40 \ kg = m`

The falling rock has a mass of 40 kilograms.