Question

Use the KE vs. TIME graph below to answer the following questions. Express all answers in the appropriate mks uni KE vs. TIME GRAPH KE O) 20 A.) Identify when the object was not moving. 0s B.) Over what period of time was the object speeding up? 0s to 10s C.) Over what period of time was the object slowing down? 10s to 20s 15 D.) Over what period of time was the object maintaining a constant speed? 20s to 50 S 10 E.) Determine the work done during the following 3 time frames: 0 to 10 s-6J10 to 20 s -2J20 to 50 s-OJ F Determine the total work done G.) Determine the power at the following 3 times: t (s) 50 10 20 30 40

Answer 1

(1)

formula for power

P = W/t

for first frame

P = 6 J/ 10 s = 0.6 J/s

for second frame

P = -2/10 s = -0.2 J/s

for third times

P = W/t = 0J/50 s- 20 s = 0

(2)

Apply conservation of energy

PEi + KEi - Eth = PEf + KEf

mgh1 + 1/2 m vi^2 - Eth = 0 + 1/2 * m v^2

vi = 0

mgh1 - E th = 1/2 * mv^2

749*9.8(40) -98289 = 1/2 * 749 v^2

v= 22.83 m/s