Problem Set 3: Work, Energy, Power
Direction: Answer the following problems correctly. Show your complete solutions.
1. Sheila has just arrived at the airport and is dragging her suitcase to the luggage check-in desk. She
pulls on the strap with a force of 190 N at an angle of 35ยฐ to the horizontal to displace it 45 m to the
desk. Determine the work done by Sheila on the suitcase.
Given: F = 190N, ๐ = 35ยฐ, d = 45m
Unknown: W = ?
Solution: ๐ = ๐น โ ๐ โ ๐๐๐ ๐
๐ = 190๐ โ 45๐ โ ๐๐๐ 35ยฐ
๐ = 7003.75๐ฝ
Answer: ๐๐๐๐ = 7003.75 ๐ฝ
2. The Taipei 101 in Taiwan is a 1667-foot tall, 101-story skyscraper. The skyscraper is the home of the
worldโs fastest elevator. The elevators transport visitors from the ground floor to the Observation
Deck on the 89th floor at speeds up to 16.8 m/s. Determine the power delivered by the motor to lift
the 10 passengers at this speed. The combined mass of the passengers and cabin is 1250 kg.
Given: d = 1667ft = 508.1016m, v = 16.8m/s, m = 1250kg, ๐ = 9.81๐/๐ 2
Unknown: P = ?
Solution: ๐ = ๐๐๐๐
๐๐๐๐ ๐๐ ๐น๐๐๐๐โ๐ท๐๐ ๐๐๐๐๐๐๐๐๐ก
๐๐๐๐ = ๐น๐๐๐๐ ๐ท๐๐ ๐๐๐๐๐๐๐๐๐ก
๐๐๐๐ = ๐น๐๐๐๐ โ ๐๐๐๐๐๐๐ก๐ฆ
๐น = ๐๐ , ๐ฃ = ๐
๐ก= ๐ฃ๐ก
๐ฃ= ๐
๐ฃ = ๐ก = ๐
๐ฃ, ๐ = ๐น โ ๐ โ ๐๐๐ ๐
๐น = 1250๐๐ โ9.81๐
๐ 2=12262.5๐
๐ = 12262.5๐ โ 508.1016๐ โ ๐๐๐ 0 = 6230595.87๐ฝ
๐ก = ๐
๐ฃ = 508.1016๐
16.8๐/๐ 2=30.24414286๐
๐ = ๐๐๐๐
๐๐๐๐ = 12262.5๐โ508.1016๐โ๐๐๐ 0
30.24414286๐ = 6230595.87๐ฝ
30.24414286๐ = 206010 ๐๐๐ก๐ก๐
๐ = ๐น๐๐๐๐ โ ๐๐๐๐๐๐๐ก๐ฆ = 12262.5๐ โ 16.8๐
๐ =206010 ๐๐๐ก๐ก๐
Answer: ๐๐๐ค๐๐ = 206010 ๐๐๐ก๐ก๐
3. A bicycle has a kinetic energy of 124 J. What kinetic energy would the bicycle have if it had:
a. Twice the mass and was moving at the same speed?
๐พ๐ธ = 0.5 โ ๐ โ ๐ฃ 2
๐พ๐ธ1=124 ๐ฝ โ 2
๐พ๐ธ1=248 ๐ฝ
b. The same mass and was moving with twice the speed?
