Aconstant force is exerted for a short time interval on a cart that is initially at rest on an air track. this force gives the cart a certain final speed. suppose we repeat the experiment but, instead of starting from rest, the cart is already moving with constant speed in the direction of the force at the moment we begin to apply the force. after we exert the same constant force for the same short time interval, the increase in the cart’s speed

1. is equal to four times its initial speed.
2. is the same as when it started from rest.
3. cannot be determined from the information provided.
4. is equal to two times its initial speed.
5. is equal to the square of its initial speed.

To understand the behavior of the electric field at the surface of a conductor, and its relationship to surface charge on the conductor. a conductor is placed in an external electrostatic field. the external field is uniform before the conductor is placed within it. the conductor is completely isolated from any source of current or charge. part a: which of the following describes the electric field inside this conductor? it is in the same direction as the original external field.it is in the opposite direction from that of the original external field.it has a direction determined entirely by the charge on its surface.it is always zero. part b: the charge density inside the conductor is: 0non-zero; but uniformnon-zero; non-uniforminfinite part c: assume that at some point just outside the surface of the conductor, the electric field has magnitude e and is directed toward the surface of the conductor. what is the charge density η on the surface of the conductor at that point? express your answer in terms of e and ϵ0