Question

After finishing her Physics homework, Julie pulls her 50.0kg body out of the living room chair and climbs the 5.0m high flight of stairs to her bedroom. How much work does Julie do in ascending the stairs?

Answer 1

Answer: 2452.5 Joules

Explanation: The equations we will be using in the problem are Weight=Mass*(Newton's Gravitational constant(9.81m/s^2)) and Work=Force*displacement*cos(the angle between the force and displacement vectors). We won't be needing the cosine part of the work equation because the work and force vectors are parallel so the angle is 0(cos(0)=1).

We are told Julie is 50 kg and she climbs 5 meters I.e. her displacement is 5 meters. We first have to calculate the force acting on Julie so that we can determine what force we will use in the work equation. Weight is a force so we can convert her 50 kg to a weight. We do this by plugging into Weight=Mass*9.81.

Weight=50kg*9.8m/s^2=490.5 Newtons.

Now we know the force that Julie is working against while climbing the stairs. She climbs 5.0m up so her total displacement is 5 meters.

Work=(490.5 N)(5 meters)= 2452.5 Joules

Hope this helps!

For extra practice, figure out how much work Julie was to do if she had been carrying her pet dog in her arms who weighed 32 Kg while climbing 5.0 meters up the stairs.