A66.5-kg hiker starts at an elevation of 1270 m and climbs to the top of a peak 2660 m high.
(a) what is the hiker? s change in potential energy?
(b) what is the minimum work required of the hiker?
(c) can the actual work done be greater than this? explain.

Answer

given,

mass of the hiker = 66.5 kg

elevation of the hiker,h₁ = 1270 m

elevation of top peak,h₂ = 2660 m

a) Change in potential energy

    Δ PE = m g h₂ - m g h₁

    Δ PE = m g (h₂ - h₁)

    Δ PE = 66.5 x 9.8 x  (2660 - 1270)

    Δ PE = 905863 J

b) Minimum work require by the hiker will be equal to Δ PE = 905863 J

c) yes, it can be more than this, if friction is present on the surface.

it is called kinetic energy

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27