Please explain how to solve problems when an object is thrown from a top of a building/cliff/helicopter.
for example:
A helicopter on a flood relief mission flying horizontally wiht a speed u at an altitude h,has to drop a food packet for a victim standing on the ground.At what distance from the victim should the food packet be dropped?
 
In these kind of problems,should we use formulae of projectile motion?

Asked by Benjamin | 19th Sep, 2015, 05:51: PM

Expert Answer:

The velocity of the food packet at the time of release is u and it is horizontal. The vertical velocity of the time of release is zero.
Vertical motion: Let t be the time taken by the packet to reach the victim, we get,
begin mathsize 14px style straight H equals 1 half gt squared or straight t equals square root of fraction numerator 2 straight H over denominator straight g end fraction end root end style     ... (1)
 
Horizontal motion: Let D be the horizontal distance travelled by the packet, we get, 
D=ut.
Substituting the value of t from equation (1) in D=ut, we get,
begin mathsize 14px style straight D equals straight u square root of fraction numerator 2 straight H over denominator straight g end fraction end root end style
Therefore, the distance between the victim and the packet at the time of release is,
begin mathsize 14px style square root of straight D squared plus straight H squared end root equals square root of fraction numerator 2 straight u squared straight H over denominator straight g end fraction plus straight H squared end root end style

Answered by Faiza Lambe | 19th Sep, 2015, 10:38: PM