1.) IP A sled slides without friction down a small, ice-covered hill. On its fir
ID: 1595718 • Letter: 1
Question
1.) IP A sled slides without friction down a small, ice-covered hill. On its first run down the hill, the sled starts from rest at the top of the hill and its speed at the bottom is 7.50 m/s. On a second run, the sled starts with a speed of 1.50 m/s at the top. What is the speed of the sled at the bottom of the hill on the second run?
Vbottom,2= ________m/s
2.) Pushing on the pump of a soap dispenser compresses a small spring. When the spring is compressed 0.55 cm , its potential energy is 0.0025 J
What is the force constant of the spring?
k= ______n/m
What compression is required for the spring potential energy to equal 0.0084 J ?
x=_______m
3). Suppose that the coefficient of kinetic friction between Zak's feet and the floor, while wearing socks, is 0.250. Knowing this, Zak decides to get a running start and then slide across the floor.
If Zak's speed is 3.00 m/s when he starts to slide, what distance d will he slide before stopping?
________ m
Explanation / Answer
here,
for first run
the speed of the sled at bottom , v = 7.50 m/s
let the height of hill be h
using conservation of energy
0.5 * m *v^2 = m*g*h
0.5 * 7.50^2 = 9.8 * h
h = 2.86 m
(a)
when the initial speed , v0 = 1.50 m/s
using conservation of energy
1/2*m*v'^2 - 1/2*m*v0^2 = m*g*h
0.5*v'^2 - 0.5*v0^2 = g*h
0.5*v'^2 - 0.5*1.50^2 = 9.8*2.86
v' = 7.64 m/s
(b)
the speed of the sled at the bottom of the hill after the second run is 7.64 m/s.
Vbottom = 7.64 m/s
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