1. if a person is walking up the stairs is carrying a box which hasa mass of 10k
ID: 1666398 • Letter: 1
Question
1. if a person is walking up the stairs is carrying a box which hasa mass of 10kg, how much work has the person done on the box whenhe or she reaches the top of the stairs? other information: theheight of the stairs is 20m. The chioces for answers are: a. 2000J,b. 200J, c. 160 J, d. none of these, e. there is not enough infoavailable to answer the question.2. The person in the above question drops the box from theside edge of the stair landing straight down the side. It takes twoseconds to hit the ground. How much kinetic energy does the boxpossess when it hits the ground? a. 2000J, b. 200J, c. 320J, d. none of these.
Thanks! Joanne
2. The person in the above question drops the box from theside edge of the stair landing straight down the side. It takes twoseconds to hit the ground. How much kinetic energy does the boxpossess when it hits the ground? a. 2000J, b. 200J, c. 320J, d. none of these.
Thanks! Joanne
Explanation / Answer
work done by the gravitational force doesn't depend how the objecttravelled, it depends on starting-point and finishing-point: W=m.g.h=10*9.8*20=1960 (J)=>2000 J (b)when reached the ground its velocity is=g.time=9.8*2=19.6(m/s) kinetic energy lost=m.v2/2=1920.8 (J)=> result is2000 J..(depending the value of g taken)
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