Answer: C. Steel
Explanation: When a sound wave travels through a solid body consisting
of an elastic material, the velocity of the wave is relatively
high. For instance, the velocity of a sound wave traveling
through steel (which is almost perfectly elastic) is about
5,060 meters per second. On the other hand, the velocity
of a sound wave traveling through an inelastic solid is
relatively low. So, for example, the velocity of a sound wave
traveling through lead (which is inelastic) is approximately
1,402 meters per second.
Answer:

Explanation:
The force on the point charge q exerted by the rod can be found by Coulomb's Law.

Unfortunately, Coulomb's Law is valid for points charges only, and the rod is not a point charge.
In this case, we have to choose an infinitesimal portion on the rod, which is basically a point, and calculate the force exerted by this point, then integrate this small force (dF) over the entire rod.
We will choose an infinitesimal portion from a distance 'x' from the origin, and the length of this portion will be denoted as 'dx'. The charge of this small portion will be 'dq'.
Applying Coulomb's Law:

The direction of the force on 'q' is to the right, since both charges are positive, and they repel each other.
Now, we have to write 'dq' in term of the known quantities.

Now, substitute this into 'dF':

Now we can integrate dF over the rod.

Answer: 7.53 μC
Explanation: In order to explain this problem we have to use the gaussian law so we have:
∫E.dS=Qinside/εo we consider a gaussian surface inside the conducting spherical shell so E=0
Q inside= 0 = q+ Qinner surface=0
Q inner surface= 1.12μC so in the outer surface the charge is (8.65-1.12)μC=7.53μC
Answer:
875 N
Explanation:
From this question, you didn't state the time taken for the bumper car to move or to hit the other bumper car. In calculations of force, time is often needed, because
Force = mass * acceleration, while
Acceleration = velocity / time, basically
Force = mass * velocity / time.
We have our mass, we have our velocity, but we haven't time. So, for this calculation, I'd assume our time to be 1s.
Going by the formula I stated, we can then say that
Force = 250 * 3.5 / 1
Force = 875 N
This means the force my bumper car have while moving at 3.5 m/s for an estimated time of 1s is 875 N