A girl throws a rock horizontally,with a velocity of 10 m/s,from a bridge.It falls 20 m to the water below.How far does the rock travel horizontally before striking the water,assuming negligible air resistance?
A)14 m
B)16 m
C)20 m
D)24 m

Question

Quizplus · Accepted Answer

The horizontal motion of the rock is independent of its vertical motion. Therefore, we can use the formula d = vt, where d is distance, v is the velocity, and t is time. In this case, we are trying to find d, so we need to rearrange the formula to solve for t: t = d/v. We know v = 10 m/s and we want to find t when the rock hits the water, so we can use the vertical motion formula h = 1/2gt^2, where h is the height (20 m) and g is the acceleration due to gravity (9.8 m/s^2). Solving for t, we get t = sqrt(2h/g) = sqrt(40/9.8) = 2.02 s (rounded to two decimal places). Now we can use the horizontal motion formula to find the distance traveled: d = vt = 10 m/s x 2.02 s = 20.2 m (rounded to one decimal place). Therefore, the answer is C) 20 m.

A Girl Throws a Rock Horizontally,with a Velocity of 10