Question

Hanging over the railing of a bridge, you drop an egg (no initial velocity) as you throw a second egg downward. Which curves in Fig 2-21 give the velocityfor- (a) the dropped egg and (b) the thrown egg? (Curves A and B are parallel, so are C, D and E, so are F and G)

Short answer

(a) D curve gives the velocity for the dropped egg.

(b) E curve gives the velocity for the thrown egg.

Step-by-step solution

Given information

Curves are given in figure 2.21

Free fall body

This problem is based on the concept of free fall. Free fall is any motion of a body whereas gravity is the only force acting upon it.

(a) To describe the curve gives the velocity for dropped egg

The dropped egg follows the free-fall motion and hence it has an initial velocity of zero. As it moves downwards, its velocity goes on increasing but in the negative direction. By observing the above graph, we can conclude that theD curve gives the velocity for the dropped egg.

(b) To describe the curve gives the velocity for the thrown egg

The egg can be thrown downwards or upwards. The egg thrown in the upward direction would be acted upon by gravity and its velocity would start decreasing. At some point in time, it would become zero and then it would start increasing but in the negative direction. This is represented by graph C.

The egg is thrown with some velocity in the downward direction. Its velocity goes on increasing with time in a negative direction. This is represented by graph E.

As only gravitational force is acting on the egg, it has gravitational acceleration similar to the first case. Hence the curve should also have the same slope as in the first case. So, the curve should be parallel to the Curve D.By observing the above graph, we can conclude that,

Curves C and E can give the velocity for the thrown egg.

However, in this problem, it is specifically mentioned that the eggs are thrown in the downward direction, therefore it is best represented by curve E.