Hey I\'m going through my physics homework and hit this problem and I\'m stumped
ID: 1377620 • Letter: H
Question
Hey I'm going through my physics homework and hit this problem and I'm stumped.
Gayle runs at a speed of 4.20 m/s and dives on a sled, initially at rest on the top of a frictionless snow-covered hill. After she has descended a vertical distance of5.00 m, her brother, who is initially at rest, hops on her back and together they continue down the hill. What is their speed at the bottom of the hill if the total vertical drop is 15.0 m? Gayle's mass is 49.5 kg, the sled has a mass of 5.10 kg and her brother has a mass of 30.0 kg.
Explanation / Answer
initial PE = (m1 +m2) gh + Mb gh
PEi =((49.5 +5.1 )* 9.8 * 15) + ( 30 *9.8* (15-5))
PEi = 10966.2 Joules
inital KE = 0.5 MV^2 = 0.5 * 49.5 * 4.2 *4.2
initial KE = 436.59 Joules
total inital Enegry E = 10966.2 + 436.59
TE = 11402.79 Joules
total mass = 40.5 + 5.1 + 20 = 74.6 Kgs
so use 0.5MV^2 = 11402.79
v^2 = sqrt ( 2 * 11402.79/74.6)
V = 17.48 m/s -------------<<<<<<<<<<<<<<<<<-Answer