Question

A helicopter lifts a 72 kg astronaut 15 m vertically from the ocean by means of a cable. The acceleration of the astronaut is g/10. How much work is done on the astronaut by (a) the force from the helicopter and (b) the gravitational force on her

Answer 1

(a) 1058.4 J

(b) -10584 J

Step-by-step explanation:

Parameters given:

Mass of astronaut, m = 72 kg

Distance moved by astronaut, d = 15 m

(a) WORK DONE BY FORCE FROM THE HELICOPTER

Work done is given as the product of Force applied to a body and the distance moved by the body:

W = F * d

The force from the helicopter is given as:

F = m * a

where a = acceleration of the astronaut due to the helicopter

Therefore, the work done is given as:

W = m * a * d

W = 72 * g/10 * 15

W =
`(72 * 9.8 * 15)/(10)`

W = 1058.4 J

(b) WORK DONE BY FORCE OF GRAVITY

W = F * d

The force of gravity is given as:

F = -m * g

where g = acceleration due to gravity

The negative sign is due to the fact that the astronaut moves in an opposite direction (upwards) to the force of gravity (Gravity acts downwards)

Therefore, the work done is given as:

W = -m * g * d

W = -72 * 9.8 * 15

W = -10584 J