An electrical motor provides 0.50w of mechanical power. how much time will it take motor to lift a 0.1 kg mass at constant speed form to a shelf 2.0 m above the floor?

a. 0.25s
b. 0.40s
c. 1.0s
d. 4.0s

d. 4.0s

Explanation:

Mass = 0.1 kg

g = acceleration due to gravity = 10 m/s^2

Force = 0.1 × 10 = 1N

Distance = 2m

Time = force × distance / power

        = 1 × 2/0.5

        = 4.0 s

The right option is d. 4.0s

power out to power in less than 100%

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.