Calculating Work and Kinetic Energy in a Vertical Helicopter Lift

In summary, in order to lift a 72.7 kg astronaut 16.9 m vertically out of the ocean, a helicopter exerts a constant upward acceleration of 7.23 m/s^2. The work done by the helicopter on the astronaut is (7.23 m + mg) (16.9) Joules.
  • #1
shenwei1988
24
0
A helicopter is used to lift a 72.7 kg astronaut 16.9 m vertically out of the ocean by means of a cable. The astronaut rises with constant upward acceleration of magnitude 7.23 m/s2 until she reaches the helicopter.

a) How much work is done by the helicopter on the astronaut?


W=1/2MV^2=FS


first try: V^2=2as W=mas=8882.9949J wrong
second try: F=mg W=mgh=12052.8603J wrong

someone help me please, thank you so much!
 
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  • #2
First find the force required to lift the person. Then use work is force times displacement to find the work.
 
  • #3
is the force mg ?
 
  • #4
Use Newton's Second Law.

F = m*a

Force of helicopter - mass of astronaut * g = mass of astro * 7.23

Therefore the Force the helicopter must exert is 7.23 m + mg

Work = Force x Distance, so its just (7.23 m + mg) (16.9) Joules. Good luck!
 
  • #5
yeah, i forgot to add the force of helicopter. thank you man!
 

1. What is work and kinetic energy?

Work and kinetic energy are two concepts in physics that are closely related. Work is defined as the amount of energy transferred to an object by a force, while kinetic energy is the energy an object possesses due to its motion. In simpler terms, work is the effort put into moving an object, while kinetic energy is the resulting energy of that movement.

2. How are work and kinetic energy related?

Work and kinetic energy are directly proportional to each other. This means that the more work is done on an object, the more kinetic energy it will gain. In mathematical terms, the work done on an object is equal to the change in its kinetic energy.

3. What is the unit of measurement for work and kinetic energy?

The unit of measurement for both work and kinetic energy is joules (J). This unit is equivalent to the amount of work done by a force of one newton (N) exerted over a distance of one meter (m).

4. Can work and kinetic energy be negative?

Yes, both work and kinetic energy can be negative. This occurs when the direction of the force and the direction of the object's movement are opposite. In this case, the work done on the object and its resulting kinetic energy will be negative.

5. How does friction affect work and kinetic energy?

Friction is a force that opposes the movement of an object and can decrease the amount of work done on an object. This means that friction can also decrease the kinetic energy of an object. However, the work done against friction results in heat energy, which is a form of kinetic energy at the molecular level.

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