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3 years ago

A 50.0 kg woman climbs a flight of stairs 6.00 m high in 15.0 s. How much power does she use.

Physics

1 answer:

WITCHER [35]3 years ago

6 0

Her weight = (mass) · (gravity) = (50kg) · (9.8 m/s²)

Work = (weight) · (height) = (50kg) · (9.8 m/s²) · (6 m)

Power = (work) / (time) = (50kg) · (9.8 m/s²) · (6 m) / (15 s)

Power = (50 · 9.8 · 6 / 15) · (kg · m² / s³)

Power = 196 (kg · m / s²) · (m) / s

Power = 196 Newton-meter/second

<em>Power = 196 watts</em>

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Explanation:

Ball is thrown downward:

initial velocity, u = - 20 m/s (downward)

height, h = - 60 m

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v = 39.69 m/s

(b) Let t be the time taken

Use First equation of motion

v = u + a t

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t = 2 second

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initial velocity, u = 20 m/s (upward)

height, h = - 60 m

Acceleration due to gravity, g = - 9.8 m/s^2 (downward)

Use third equation of motion

$v^{2}=u^{2}+2as$

$v^{2}=(-20)^{2}+2\times 9.8 \times 60$

v = 39.69 m/s

(d) Let t be the time taken

Use First equation of motion

v = u + a t

- 39.69 = + 20 - 9.8 t

t = 6.09 second

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