# physics

posted by .

A labour is throwing 12 bricks per min from the ground and these just reach the roof which is 3.3 meters high. ifthe weight of each bricks be 3.75 kg then find the horse power with which the labour is working.

• physics -

Power is rate of work.

Work is force times displacement.

Force is weight of each brick under gravity. Measure weight in [kgf] (kilogram-force: the weight of 1[kg] in normal gravity).

The conversion rate to metric horsepower is: 1[hp] = 75 [kgf·m/s]

Use: P = Ws/t
Where:
(1/t) = 12[/min] = 0.2[/s]
s = 3.3[m]
W = 3.75[kgf]

• physics -

12 bricks/min*(1min/60s)=0.2bricks/s

m=(3.75kg/brick)

F=mg=(3.75kg/brick)*9.8m/s^2=36.75N/brick

d=3.3m

Since Power=Work/t(s)=F*d/t

Power=(36.75N/brick)*(0.2bricks/s)*(3.3m)=24.3 W

***Bricks cancel leaving (N*m)/s

24.3 W*(1hp/745.70 W)=0.0325 hp

## Similar Questions

1. ### math (algerbra)

A bricklayer's assistant starts building a wall, laying 50 bricks per hour. Two hours later the master comes and lays down 80 bricks per hour. x= number of hours since the assistant has been laying. Qusestion-------- Write expressions …
2. ### Math

Julia wants to build another garden wall, 10 bricks long and 3 bricks high. Can she build it with red and white bricks, so that no two bricks of the same color are next to each other?
3. ### Math

A pile of bricks has 85 bricks in the bottom row, 81 bricks in the second row up, 77 in the third, and so on up to the top row that contains only 1 brick. How many bricks are in the 12th row?
4. ### Math

You plan to construct a brick wall measuring 4.5 m in length, 1.2 m high, and 0.5 m in width. If a brick measures 20 cm x 9 cm x 5 cm, how many bricks will you need?
5. ### MATH

a pile of bricks has 85 bricks in the bottom row, 79 bricks in the second row, 73 in the third row, and so on until there is only 1 brick in the top row. how many bricks are in the 12th row?
6. ### Physics

What power is needed to lift a 358 crate of bricks from the ground to the top of a 25.0 -high building in 1 minute?
7. ### math

bricks are stacked in 20 rows such that each row has a fixed number of bricks more than the row above it. the top row has 5 bricks and the bottom row 62 bricks. how many bricks are in the stack?
8. ### physics

A brick weight 17.8N and is resting on the ground. Its dimensions are 0.203mx0.089mx0.0570m. A number of the bricks are then stacked on top of this one. What is the smallest number of whole bricks (including the one on the ground) …
9. ### Physics

A laborer is throwing 12 bricks per min from the ground and these just reach the roof which is 3.3 meters high. if the weight of each bricks be 3.75 kg then find the horse power with which the laborer is working.
10. ### Math

Building Bricks A child is playing with building bricks like this one. He decides to build the simple tower shown. How many bricks would he need to build this tower?

More Similar Questions