Question #114453

A 48.0 kg in-line skater begins with a speed of 2.2 m/s. Friction also does (-150) J of work on her. Assume that se did not push on the ground any more. If her final speed is 5.9 m/s,

a) determine the change (final-initial) in her gravitational potential energy.

b) By how much, and in which direction (up or down), has her weight changed?

Please answer using grade 11 Conservation of Energy and Momentum .

Expert's answer

As per the given question,

mass of the line skater "(m)=48 kg"

speed of the line skater "(u)=2.2 m\/sec"

work done by friction force "(w)=-150J"

her final speed "(v)=5.0m\/sec"

a) Applying the conservation of energy,

Initial potential energy "(U_1)=\\dfrac{mu^2}{2}"

Final energy "(U_2)=\\dfrac{mv^2}{2}-150"

so, change in PE"=\n\\dfrac{48\\times 5.9^2}{2}-\\dfrac{48\\times 2.2^2}{2}-150=(835.44-232.32-150 )J=453.12J"

b)Weight of the skater is working downwards, because as she is moving downwards, her speed is getting increase, it means it is getting accelerate towards the ground.

Learn more about our help with Assignments: MechanicsRelativity

## Comments

## Leave a comment