# physics

A stonemason lifts a small boulder weighing Fw = 80 N from the ground onto a height = 1.50 m wall in the time t = 2.0 s.

Using the values in the problem, calculate how much work she does.

What power does she develop in watts?

What power does she develop in kilowatts?

What power does she develop in horsepower?

1. 👍 0
2. 👎 0
3. 👁 557
1. work = force * distance in direction of force
= 80 * 1.5 = 120 Joules

power
Hey we know that cold by now
= 120 Joules / 2 seconds = 60 Watts

60 watts * 1 kw/1000 watts = 0.06 kw

0.06 kw * 1.341 hp/kw = 0.08 Hp

I figure with an electric motor you get about 1 hp per kw after allowing for efficiency

1. 👍 1
2. 👎 0
2. work=force(height)
powerWatts= workJoules/timeinSec

powerKwatts=powerwatts/1000

powerHP=powerwatts/746

1. 👍 0
2. 👎 0
👨‍🏫
bobpursley

## Similar Questions

1. ### Physics

In starting an exercise, a 1.60-m tall person lifts a 2.10 kg book from the the ground so it is 2.20m above the ground. What is the potential energy of the book relative to (a) the ground,and(b) the top of the persons head? (c)

2. ### general biologt

Water freezes in the crack in this boulder and expands. Over time pieces of the boulder will break off. What type of wathering effects is this an example of? a. wedging b. hydration c. carbonation d. reduced pressure

3. ### Math

13. A catapult launches a boulder with an upward velocity of 148 ft/s. The height of the boulder (h) in feet after t seconds is given by the function h = –16t² + 148t + 30. How long does it take the boulder to reach its maximum

4. ### Science

A Crane lifts a cargo Box 10M off the ground if the Crane lifts the cargo Box toys as high the potential energy will be increased by

1. ### Science

Two rocks of very different sizes are dropped from the same height. Which value will be different for the two rocks?(1 point) the acceleration of the rocks the velocity of the rocks after a few seconds the downward pull of gravity

2. ### Physics

The Alert Hiker: An alert hiker sees a boulder fall from the top of a distant cliff and notes that it takes 1.3s for the boulder to fall the last third of the way to the ground. a.What is the height of the cliff in meters? b.If in

3. ### physics

A cheerleader lifts his 62.2 kg partner straight up oﬀ the ground a distance of 0.89 m before releasing her. The acceleration of gravity is 9.8 m/s 2 . If he does this 19 times, how much work has he done? Answer in units of J

4. ### physics

Read the scenario. A boulder with a mass of 50 kg is sitting in a backyard. If the boulder were half the mass, what could be said about the gravitational force on the boulder? It would be reduced to one quarter. It would not

1. ### Calc II

A worker on scaffolding 65 ft above the ground needs to lift a 390 lb bucket of cement from the ground to a point 20 feet above the ground by pulling on a rope weighing 5 lb/ft. How much work is required?

2. ### physics/calc

A worker on scaffolding 75 ft above the ground needs to lift a 500 lb bucket of cement from the ground to point 30 ft above the ground by pulling on a opre weighing .5 lb/ft. how much work is required? I know to use the Work

3. ### physics

An athlete whose mass is 94.0 is performing weight-lifting exercises. Starting from the rest position, he lifts, with constant acceleration, a barbell that weighs 600 . He lifts the barbell a distance of 0.50 in a time of 2.2 .

4. ### physics

In a canyon between two mountains, a spherical boulder with a radius of 1.4 m is just set in motion by a force of 230 N. The force is applied at an angle of 73.9 ◦ measured with respect to the radius of the boulder. What is the