The sleds speed when the spring returns toits uncompressed length is v = 0.03 m/s.
<u>Explanation</u>:
Given,
force constant = 42 N/cm = 0.42 N/m, mass m = 68 kg, spring x = 0.39 m
The potential energy, U, stored in the spring is
U = 1/2 kx^2
= 1 / 2
0.42
(0.39)^2
= 0.032 J
All its potential energy has been converted into kinetic energy since it has a uncompressed length.
K = 1/2 mv^2
v = sqrt (2K / m)
= √(( 2
0.032) / 68)
v = 0.03 m/s
.
Explanation:
velocity of disc 
lets call (h) 1 m to make it simple.
= 3.614 m/s
m/s pointing towards this:


velocity of hoop=
lets call (h) 1m to make it simple again.
m/s
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The disc is the fastest.
While i'm on this subject i'll show you this:
Solid ball 
solid disc 
hoop 
The above is simplified from linear KE + rotational KE, the radius or mass makes no difference to the above formula.
The solid ball will be the faster of the 3, like above i'll show you.
solid ball: velocity 
let (h) be 1m again to compare.
m/s
solid disk speed 
uniform hoop speed 
solid sphere speed 
Answer:
b
Explanation:
see how far the bullet goes
Answer:
The difference between the lower mantle and the oceanic crust is first their respective locations, pressure and temperature-- the pressure and temperature increases with depth in the earth this the mantle is more hot and under great pressure than the crust.
Explanation: