Work, power, acceleration problem

In summary, a helicopter with a mass of 810 kg accelerates straight up from the roof of a hospital, reaching a speed of 7.0 m/s in 3.5 s and a height of 8.2 m. The lifting force, FL, does work by generating an average power of 33,453 watts.
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jehan4141
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A helicopter, starting from rest, accelerates straight up from the roof of a hospital. The lifting force does work in raising the helicopter. An 810-kg helicopter rises from rest to a speed of 7.0 m/s in a time of 3.5 s. During this time it climbs to a height of 8.2 m. What is the average power generated by the lifting force?

M = 810 kg
V0 = 0 m/s
Vf = 7 m/s
t = 3.5 s
y = 8.2 m

Force acting on helicopter: mg and FL (the lifting force)

It is accelerating upward. Find acceleration, a:

Vf = Vo + at
a = (Vf - Vo)/t
a = 2 m/s2

FL - mg = ma
FL = mg + ma
FL = 810(9.8+2)
FL = 9558 N

P = FL x avg V = 9558 N x 3.5 m/s
P = 33453 watts?
 
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  • #2
Looks alright. You might want to express the result using the appropriate number of significant figures.
 
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Thank you so much! My quiz is tomorrow and I wasn't sure how to do this type of problem!
 
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1. What is the difference between work and power in physics?

Work and power are both physical quantities that describe the amount of energy used or transferred in a given amount of time. However, work is a measure of the energy used to move an object, while power is the rate at which work is done or energy is transferred.

2. How do you calculate work in a physics problem?

Work can be calculated by multiplying the force applied to an object by the distance it moves in the direction of the force. The formula for work is W = F x d, where W is work in joules, F is force in newtons, and d is distance in meters.

3. What is the relationship between power and time in a physics problem?

The relationship between power and time is that power is equal to the amount of work done divided by the time it takes to do that work. This can be represented by the formula P = W/t, where P is power, W is work, and t is time.

4. How do you calculate acceleration in a physics problem?

Acceleration is the rate of change of an object's velocity. To calculate acceleration, you can use the formula a = (vf - vi) / t, where a is acceleration, vf is final velocity, vi is initial velocity, and t is time.

5. Can you explain the difference between average and instantaneous acceleration?

Average acceleration is the overall change in velocity over a given period of time, while instantaneous acceleration is the acceleration at a specific moment in time. Average acceleration can be calculated by dividing the change in velocity by the change in time, while instantaneous acceleration can be found by taking the derivative of the velocity function with respect to time.

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