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± A Sliding Crate of Fruit A crate of fruit with a mass of 34.5 kg and a specifi

ID: 1510439 • Letter: #

Question

± A Sliding Crate of Fruit

A crate of fruit with a mass of 34.5 kg and a specific heat capacity of 3500 J/(kgK) slides 7.70 mdown a ramp inclined at an angle of 38.0 degreesbelow the horizontal.

Part A

If the crate was at rest at the top of the incline and has a speed of 2.50 m/s at the bottom, how much work Wf was done on the crate by friction?

Use 9.81 m/s2 for the acceleration due to gravity and express your answer in joules.

SubmitHintsMy AnswersGive UpReview Part

Correct

The frictional force opposes the motion of the crate, so the work done on the crate by friction must be a negative quantity.

Part B

If an amount of heat equal to the magnitude of the work done by friction is absorbed by the crate of fruit and the fruit reaches a uniform final temperature, what is its temperature change T?

± A Sliding Crate of Fruit

A crate of fruit with a mass of 34.5 kg and a specific heat capacity of 3500 J/(kgK) slides 7.70 mdown a ramp inclined at an angle of 38.0 degreesbelow the horizontal.

Part A

If the crate was at rest at the top of the incline and has a speed of 2.50 m/s at the bottom, how much work Wf was done on the crate by friction?

Use 9.81 m/s2 for the acceleration due to gravity and express your answer in joules.

Wf = -1500   J  

SubmitHintsMy AnswersGive UpReview Part

Correct

The frictional force opposes the motion of the crate, so the work done on the crate by friction must be a negative quantity.

Part B

If an amount of heat equal to the magnitude of the work done by friction is absorbed by the crate of fruit and the fruit reaches a uniform final temperature, what is its temperature change T?

Explanation / Answer


potential energy at the top Ui = m*g*L*sintheta

kinetic energy at the top = Ki = 0


total energy at the top = Ei = ui + ki = m*g*L*sintheta

potential energy at the bottom Uf = 0

kinetic energy at the bottom = Kf = 0.5*m*v^2


total energy at the bottom = Ef = uf + kf = 0.5*m*v^2

from work energy theorem

fWf = Ei - Ei


Wf = (0.5*34.5*2.5^2)-(34.5*9.8*7.7*sin38) = -1500 J

+++++++++++++++++++++++


amount of heat gained Q = m*C*dT

Q = Wf


m*C*dT = 1500

34.5*3500*dT = 1500


dT = 0.0124 degrees