# Physics

"A workman sitting on top of a roof of a house drops his hammer. The roof is smooth and slopes at an angle of 30.0 degrees to the horizon. It is 32m long and its lowest point is 32m from the ground. How far from the house's wall is the hammer when it hits the ground?" (28m)

I thought I would firstly find the acceleration of the hammer down the roof.

ma = Fgx
a = (9.81)(sin30) = 4.905

Using the acceleration, I found the final velocity at the roof.

Vf^2 = 0 + 2(4.905)(32)

However, is the initial velocity 0?

After I found Vf, I used that as the initial velocity to find the time it would take for the hammer to fall to the ground, and then used that time to find the horizontal distance. I don't get the answer though...am I even doing this correctly?

1. 👍
2. 👎
3. 👁
1. Your Vf (velocity at the edge) is correct. However, now you have to break that into a horizonal velocity, and a vertical velocity.

Verticalatroofedge=sqrt (2*4.9*32)
horizontal component=sin30*sqrt( )
vertical component= cos30*sqrt( )

now you can find the time down...

32=verticalcompnent*t+1/2 g t^2 solve for t.

then, horizonal distance= vhorizontal component*t

1. 👍
2. 👎
👤
bobpursley
2. I would use energy to get the speed at the roof edge.
(1/2) m v^2 = m g * 32 sin 30
v^2 = 9.81 * 64 (.5) = 313.9
v = 17.7 m/s which agrees with you so far
However now you have two problems, a horizontal problem and a vertical problem.
The horizontal speed is 17.7 cos 30 = 15.3 m/s and remains constant
The initial vertical speed down is 17.7 sin 30 = 8.85
so
32 = 8.85 t + .5*9.81 t^2
solve that for t
then distance horizontal = 8.85 t

1. 👍
2. 👎

## Similar Questions

1. ### physics

A stuntman plans to run across a roof top and then horizontally off it to a land on the roof of the next building . The roof of the next building is 4.8 m below the first one and 6.2 m away from it . Can he make the jump if his

2. ### Southern Union

A large building has an inclined roof. The length of the roof is 64.0 m and the angle of the roof is 20.0° below horizontal. A worker on the roof lets go of a hammer from the peak of the roof. Starting from rest, it slides down

3. ### physics

a brick is dropped form the roof of a building. On the way down it passes a 2m high window and is observed to pass from the top to the bottom of the window in 0.25s. (a) How fast was it moving when it passed the top of the window?

If wind blows at a speed of 30 m/s over the roof of your house, what is the pressure diference on your roof between the air inside and the air outside? What net force does this produce on a roof having an area of 175 m^2? 1.3

1. ### math

22. Bob and James are finishing the roof of a house. Working alone, Bob can shingle the roof in 10 hours. James can shingle the same roof in 16 hours. How long will it take them working together to shingle the roof? Round your

2. ### Math

A hurricane wind blows across a 6.00 m times 15.0 m flat roof at a speed of 190 km/hr. What is the pressure difference? Use 1.28 kg/m^3 for the density of air. How much force is exerted on the roof? If the roof cannot withstand

3. ### physics

a worker lays a rubber handled 0.500kg hammer down a sloped roof. it slides down the roof to a level portion of the roof where it slides another 2.oo m long this horizontal surface. the coefficient of friction between the rubber

A boy climbs to the roof of his house and drops a 0.40 kg rubber ball from the 7.5-meter peak of the house. How much energy was lost in the process? So I got 48 J is this correct? The bounce takes place over a 170 ms time

1. ### Physics

A roof tile falls from rest from the top of a building. An observer inside the building notices that it takes 0.2s for the tile to pass her window, whose height is 1.6m. How far above the top of this window is the roof?

2. ### Physics

After delivering his toys in the usual manner, Santa decides to have some fun and slide down an icy roof. The roof is 7 m in length and makes an angle of 41° with the horizontal. He starts from rest at the top of the roof and

3. ### Physics

My problem question: "A ball is thrown up onto a roof, landing 4.0 seconds later at a height of 20.0 m above where it was thrown. The ball's velocity vector upon landing on the roof top was angled 60 degrees to the horizontal flat

4. ### math

A carpenter is constructing a triangular roof for a storage shed as shown in the figure. Part A isosceles triangle = 15 degrees and 15 degrees length of bas is 45 How high will the peaks of the rise above in the top of the shed?