A weight-lifting athlete raises a mass of 160 kg through a vertical distance of 1.4 m. What force did he apply to the mass to lift it and how much energy did he use for that lift?

1568N

2195.2J

Explanation:

Given parameters:

Mass of the weight = 160kg

Distance  = 1.4m

Unknown:

Force applied to lift the weight = ?

Energy expended  = ?

Solution:

The force applied in moving a body with a given mass through a distance is the weight;

     Force applied  = mg

Where m is the mass

           g is the acceleration due to gravity

i.  Applied force = 160 x 9.8  = 1568N

ii. The energy used to lift the weight is given as;

     Energy  = mgh

h is the vertical distance

     Energy  = 1568 x 1.4  = 2195.2J