Because the Moon has a very small surface area compared to other spacial geo-bodies, it has cooled down much faster than Earth. Any water on the moon would freeze.
Initially, the spring stretches by 3 cm under a force of 15 N. From these data, we can find the value of the spring constant, given by Hook's law:
where F is the force applied, and
is the stretch of the spring with respect to its equilibrium position. Using the data, we find
Now a force of 30 N is applied to the same spring, with constant k=5.0 N/cm. Using again Hook's law, we can find the new stretch of the spring:
Answer:
temperature change is 262.06°K
Explanation:
given data
mass = 0.07 kg
velocity = 258 m/s
to find out
what is its temperature change
solution
we know here
heat change Q is is equal to kinetic energy that is
KE = 0.5 × m× v² ...........1
here m is mass and v is velocity
KE = 0.5 × 0.07 × 258²
KE = 2329.74 J
and we know
Q = mC∆t .................2
here m is mass and ∆t is change in temperature and C is 127J/kg-K
so put here all value
2329.74 = 0.07 × 127 × ∆t
∆t = 262.06
so temperature change is 262.06°K
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.
