I think to an observer outside the train, the speed of the ball will actually look like more than the speed of the train.
Answer: Option (b) is the correct answer.
Explanation:
It is given that a positive test charge q is released from rest at a distance r away from a charge of +Q and a distance 2r which is away from a charge of +2Q.
Then test charge to the right immediately after being released.
Therefore, the net force will be as follows.
F = 
= 
= 
F =
> 0
Thus, we can conclude that the test charge move to the right immediately after being released.
Answer:
Copper
Explanation:
Since the heat of Fussion of copper is less than that for nickel it means copper melts faster than nickel.
Answer:
1.58 W
Explanation:
Since the sound spreads uniformly in all directions, it must be in a form of a circle with radius of 12 m. So the area of the circle is

From the intensity of the sound we can calculate the power at 12 m

Object distances are always negative according to the Cartesian sign convention