# Physical Science

posted by .

A rock thrown straight up climbs for 2.50 s,the falls to the ground. Neglecting the air resistance, with wat velocity did the rock strike the ground?

• Physical Science -

The same speed that it was thrown, but travelling in the opposite direction. You can conclude that from an energy conservation argument.

The kinetic energy when thrown and landing equals the potential energy at the highest point of the trajectory.

(1/2) M V^2 = M g H
The time of flight T satisfies
H = (V/2)T
where T is the time of flight.

Thus V^2 = 2 g H = g T V
V = g T

There is an easier way to reach the same result, but I didn't see it.

T = V/g is the time it takes for the rock to reach zero velocity, which it does at the top of the trajectory.

• Physical Science -

11

## Similar Questions

1. ### Physics

A rock is thrown vertically upward with a speed of 11.0 from the roof of a building that is 70.0 above the ground. Assume free fall. In how many seconds after being thrown does the rock strike the ground?
2. ### Physics

Two rocks are thrown off the edge of a cliff that is 15.0 m above the ground. The first rock is thrown upward, at a velocity of +12.0 m/s. The second is thrown downward, at a velocity of −12.0 m/s. Ignore air resistance. Determine …
3. ### physics

A rock is thrown vertically upward with a speed of 14.0 m/s from the roof of a building that is 50.0 m above the ground. Assume free fall. In how many seconds after being thrown does the rock strike the ground?
4. ### Physics

A rock is thrown vertically from the edge of a cliff that is 500 ft high. It takes 6.5 seconds for the rock to hit the ground at the base of the cliff. Assume air resistance is negligible. (a) What was the initial velocity (magnitude …
5. ### physics

Julie throws a rock vertically upward. From a height of 64.0 meters above thehow ground. The initial velocity of the rock is 31.0 meters per second neglect air resistance How long does it take for the rock to hit the ground?
6. ### physical science

A rock thrown straight up climbs for 4.24 s, then falls to the ground. Neglecting air resistance, with what velocity did the rock strike the ground?
7. ### PHYSICS

A rock is thrown vertically upward with a speed of 14.0m/s from the roof of a building that is 70.0m above the ground. Assume free fall. In how many seconds after being thrown does the rock strike the ground?
8. ### Physics

A rock is thrown directly upward from the edge of the roof of a building that is 35.3 meters tall. The rock misses the building on its way down, and is observed to strike the ground 4.00 seconds after being thrown. Neglect any effects …
9. ### Physics

A rock is thrown directly upward from the edge of the roof of a building that is 40.2 meters tall. The rock misses the building on its way down, and is observed to strike the ground 4.00 seconds after being thrown. Neglect any effects …
10. ### Physics

A rock is thrown straight up at 22.0 m/s from a roof of a 30.0 m tall building. After rising, the rock falls on the street below. Ignoring air resistance, how much time is the rock in the air?

More Similar Questions