Jan and Len throw identical rocks off a tall building at the same time.The ground near the building is flat.Jan throws her rock straight downward.Len throws his rock downward and outward such that the angle between the initial velocity of the rock and the horizon is 30°.Len throws the rock with a speed twice that of Jan's rock.If air resistance is negligible,which rock hits the ground first?
A) They hit at the same time.
B) Jan's rock hits first.
C) Len's rock hits first.
D) It is impossible to know from the information given.

Question

Quizplus · Accepted Answer

The time it takes for an object to fall to the ground is determined by its initial vertical velocity and the acceleration due to gravity. Since both rocks are dropped from the same height, they have the same initial vertical velocity of zero. Therefore, the only difference between the two is Len's rock has an initial horizontal velocity due to its outward throw. However, this horizontal velocity does not affect the time it takes for the rock to hit the ground. Therefore, both rocks hit the ground at the same time.

Jan and Len Throw Identical Rocks Off a Tall Building