Kinetic energy lost in collision is 10 J.
<u>Explanation:</u>
Given,
Mass, 
= 4 kg
Speed, 
= 5 m/s
= 1 kg
= 0
Speed after collision = 4 m/s
Kinetic energy lost, K×E = ?
During collision, momentum is conserved.
Before collision, the kinetic energy is
By plugging in the values we get,
K×E = 50 J
Therefore, kinetic energy before collision is 50 J
Kinetic energy after collision:
Since,
Initial Kinetic energy = Final kinetic energy
50 J = 40 J + K×E(lost)
K×E(lost) = 50 J - 40 J
K×E(lost) = 10 J
Therefore, kinetic energy lost in collision is 10 J.
Q = mc<span>∆t, where:
q = energy flow
m = mass, 120 000 g
c = specific heat capacity, 4.81 J/gC
</span><span>∆t = change in temperature, ~75 (100 - 25, which is room temperature)
Substituting in the values, we get:
q = 120000 x 4.81 x 75 = 43290000 Joules = 43.29 MJ
Hope I helped!! xx
</span>
Answer:
0.02 s
160 m/s
Explanation:
Given:
Δx = 1.6 m
v₀ = 0 m/s
a = 8000 m/s²
A) Find t.
Δx = v₀ t + ½ at²
1.6 m = (0 m/s) t + ½ (8000 m/s²) t²
t = 0.02 s
B) Find v.
v² = v₀² + 2aΔx
v² = (0 m/s)² + 2 (8000 m/s²) (1.6 m)
v = 160 m/s
Explanation:
They probably put "rolls without slipping" in there to indicate that there is no loss in friction; or that the friction is constant throughout the movement of the disk. So it's more of a contingency part of the explanation of the problem.
(Remember how earlier on in Physics lessons, we see "ignore friction" written into problems; it just removes the "What about [ ]?" question for anyone who might ask.)
In this case, you can't ignore friction because the disk wouldn't roll without it.
As far as friction producing a torque... I would say that friction is a result of the torque in this case. And because the point of contact is, presumably, the ground, the friction is tangential to the disk. Meaning the friction is linear and has no angular component.
(You could probably argue that by Newton's 3rd Law there should be some opposing torque, but I think that's outside of the scope of this problem.)
Hopefully this helps clear up the misunderstanding for you.
