Math

For this problem, a person standing on the edge of a cliff throws a rock directly upward. it is observed that 2 secs later the rock is at its maximum height (in feet) and that 5 secs after that (meaning 7 seconds after being thrown) the rock hits the ground at the base of the cliff.

(a) What is the initial velocity of the rock? ft/sec.

(b) How high is the cliff? t ft.

(c) What is the velocity of the rock at time t? ft/sec.

(d)What is the velocity of the rock when it hits the ground? ft/sec.

1. 👍
2. 👎
3. 👁
1. a. V = Vo + g*t = 0
Vo - 32*2 = 0
Vo = 64 Ft/s.

b. Tf1 = Tr = 2 s. = Fall time from hmax
to top of cliff.

Tf2 = 7-Tr-Tf1 = 7 - 2 - 2 = 3 s. = Fall
time from top of cliff to gnd.

h = Vo*Tf2 + 0.5g*Tf2^2
h = 64*3 + 16*3^2 = 336 Ft. = Ht. of cliff.

c. What is time t?

d. h max = ho + -(Vo^2)/2g
h max = 336 + -(64^2)/-64 = 400 Ft. Above gnd.

V^2 = Vo^2 + 2g*h = 0 + 64*400 = 25,600
V = 160 Ft/s.

1. 👍
2. 👎

Similar Questions

1) A 20 kg rock is on the edge of a 100 m cliff. a. What potential energy does the rock possess relative to the base of the cliff? b. The rock falls from the cliff. What is the kinetic energy just before it strikes the ground? c.

2. PHYSICS HELP

A 0.26-kg rock is thrown vertically upward from the top of a cliff that is 31 m high. When it hits the ground at the base of the cliff, the rock has a speed of 29 m/s . a.Assuming that air resistance can be ignored, find the

3. birzit

boy on the edge of a vertical cliff 20 m high throws a stone horizontally upwards with a speed of 25 m\s it strikes the ground at what horizontal distance from the foot of the cliff use g=10m\s^2

4. physics

A 17-kg rock is on the edge of a 103-m cliff. (a) What potential energy does the rock possess relative to the base of the cliff? . J (b) The rock falls from the cliff. What is its kinetic energy just before it strikes the ground?

1. physics

a 20 kg rock is on the edge of a 100 m cliff . the rock falls from the cliff , what is its kinetic energy just before it hits the ground ?

2. physical science

a 2.0 kg rock sits on the edge of a cliff 12m above the beach. The rock falls off the cliff. How much kinetic energy will it have just before it hits the beach?

3. 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

A rock of mass 5kg is pushed over the edge of a cliff which is 200m high 1.ignore air resistance and calculate the speed of the rock at the bottom of the cliff. In reality air resistance cannot be ignored. The rock eventually

1. physics

A wagon is rolling forward on level ground. Friction is negligible. The person sitting in the wagon is holding a rock. The total mass of the wagon, rider, and rock is 94.0 kg. The mass of the rock is 0.350 kg. Initially the wagon

2. Physics - Torque

A student of mas 70kg wants to walk beyond the edge of a cliff on a heavy beam of mass 300kg and length 10m. The beam is not attached to the cliff in any way, it simply lays on the horizontal surface of the cliff top, with one end

3. physics

A 17 kg rock, m, is on the edge of a 105 m cliff, h, as shown in Figure 11-20. Assume that air resistance is negligible. What speed does the rock have as it strikes the ground?

4. Math

A person standing near the edge of a cliff 120 feet above a lake throws a rock upward with an initial speed of 40 feet per second. The height of the rock above the lake at the bottom of the cliff is a function of time and is