Substitution is The answer
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.
Average speed = (distance covered) / (time to cover the distance)
= (200 miles) / (5.5 hours)
= (200/5.5) mile/hour
= 36.4 miles per hour (rounded)
The type of motor that allows for constant speed regardless of load are called Geared Speed Control motors. This type of motor has a tachometer feedback device attached at the rear of the motor that gives constant feedback to the speed controller giving the advantage of constant speed regardless of load. The tachometer allows for varied frequency delivery to the motor to maintain pre-set output speed.
