Physics

A student stands at the edge of a cliff and throws a stone horizontally over the edge with a speed of 15.0 m/s. The cliff is h = 66.0 m above a flat horizontal beach.

How long after being released does the stone strike the beach below the cliff?

I got 3.67 s.

With what speed and angle of impact does the stone land?
I got 38.97 m/s for the speed, but I cannot figure out the angle. It says that the answer is in degrees "below the horizontal."

I calculated x to be 55.23m and I tried to calculate -y, but I keep getting the wrong angle. After getting -y I though I was supposed to do arctan(opp/adj) to get the angle "below the horizontal."
Please help! Thanks!

  1. 👍
  2. 👎
  3. 👁
  1. T = 3.67 s is correct for the time to impact. When thowing horizontally, the speed does not affect the time to hot the ground.

    Using conservation of energy for the speed Vf at impact,
    (1/2) Vf^2 = Vo^2/2 + g H
    (1/2) Vf^2 = (15^2)/2 + 9.8*66
    = 759.3 m^2/s^2
    Vf = 38.97 m/s

    The tangent of the angle at impact, measured below the horizontal, is Vy/Vx at impact

    theta = arctan (g*T)/15 m/s
    = arctan 35.97/15 = 67.4 degrees

    1. 👍
    2. 👎
  2. Thanks!

    1. 👍
    2. 👎
  3. It is also arcsin g*T/38.97, where 38.97 is the speed. This gives you the same angle.

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. Physics

    A person standing at the edge of a seaside cliff kicks a stone over the edge with a speed of vi = 20 m/s. The cliff is h = 53 m above the water's surface, as shown below. (a) How long does it take for the stone to fall to the

  2. Physics

    A person standing at the edge of a seaside cliff kicks a stone over the edge with a speed of 12 m/s. The cliff is 52 m above the water’s surface, as shown. 12 m/s 52 m How long does it take for the stone to fall to the water?

  3. Physics

    a stone is thrown at an angle of 30 degrees above the horizontal from the top edge of a cliff with an initial speed of 12m/s. a stop watch measures the stone's trajectory time from top of cliff to bottom to be 8s. how far out from

  4. physical science

    a stone is thrown horizontally at a speed of 5.o m/s from the top of a cliff 78.4 m high. How long does it take the stone to reach the bottom of the cliff?

  1. math

    a child standing at the edge of a cliff 100m high throws a stone vertically downwards. The stone hits the sea 4s later. Ignoring air resistance, find the initial speed with which the stone is thrown

  2. physics

    3)A soldier throws a grenade horizontally from the top of a cliff. Which of the following curves best describes the path taken by the grenade? Parabola 4)A stone is thrown horizontally from the top of a 25.00-m cliff. The stone

  3. physics

    A person standing at the edge of a seaside cliff kicks a stone over the edge with a speed of vi = 13 m/s. The cliff is h = 58 m above the water's surface, as shown below. (a) How long does it take for the stone to fall to the

  4. Physics!!! :)

    A student of mass 78 kg wants to walk beyond the edge of a cliff on a heavy beam of mass 180 kg and length 10 m. The beam is not attached to the cliff in any way, it simply lays on the horizontal surface of the clifftop, with one

  1. physics

    a person standing at the edge of a seaside cliff kicks a stone over the edge with a speed of 18 ms. The cliff is 52m above the waters surface. How long does it take for the stone to fall to the water? With what speed does it

  2. physics

    A student stands at the edge of a cliff and throws a stone horizontally over the edge with a speed of 18m/s. The cliff is 50m above a flat horizontal beach, as shown in Figure 3.20. How long after being released does the stone

  3. physics

    from a cliff of 49m high ,a man drops a stone 1s later he throes second stone . they both hit the ground at the same time . find out the speed with which he throws the second stone.

  4. Right angle trigonometry

    A sailor sights both the bottom and top of a lighthouse that is 20 and m high and which stands on the edge of a cliff. The two angles of elevation are 3 and 42. To the nearest meter, how far is the boat from the cliff?

You can view more similar questions or ask a new question.