physics/calc

posted by .

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 integral, but im not sure wat equation to use

• physics/calc -

The 500 lb bucket of cement is raised 30 ft. That part of the work required is 500x30 = 15,000 ft-lb. A 75 ft length of rope weighing 75/2 = 37.5 lb has its center of mass raised from 75/2 = 37.5 ft elevation to a situation where 30 feet is at 75 ft elevation, and a 45 feet length has a center of mass at (75+30/2) =52.5 ft. The potential energy increase of the rope is [15*37.5 + 22.5*52.5 - 37.5*37.5]= 337.5 ft lb

The total work required is 15,337.5 ft-lb

Similar Questions

1. physics

A 2 kg brick is accidentally dropped off some scaffolding from a height of 20 m above ground levele.Calculate how much potential energy it will have lost by th e time it hits the ground.
2. physics

Need help very much appreciated....Thanks....A skateboarder shoots off a ramp with a velocity of 6.5 m/s, directed at an angle of 62° above the horizontal. The end of the ramp is 1.4 m above the ground. Let the x axis be parallel …
3. Physics

A roller-coaster car with a mass of 500 kg starts at rest from point A, which is 46 m above the ground. At point B, it is 23 m above the ground.
4. calculus

A bridge worker on the top deck of a double decked bridge needs to lift a 30 kg tool box, with a cable of uniform density 2 kg/meter, from the ground 15 meters below him to the lower deck of the bridge which is 10 meters above the …
5. Physics

A skateboarder shoots off a ramp with a velocity of 6.8 m/s, directed at an angle of 56° above the horizontal. The end of the ramp is 1.1 m above the ground. Let the x axis be parallel to the ground, the +y direction be vertically …
6. 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?
7. Physics

A model rocket has a mass of 3.00 kg. It is fired so that when it is 220 m above the ground it is travelling vertically upward at 165 m/s. At that point its fuel runs out so that the rest of its flight is without power. Assume that …
8. Physic

A body was lifted 2m above the ground and then dropped. It hit the ground with 5 kg of kinetic energy. How much work was done to lift 2m Someone please help I'm stuck
9. physics

A worker on scaffolding 75 ft above the ground needs to lift a 410 lb bucket of cement from the ground to a point 25 feet above the ground by pulling on a rope weighing 5 lb/ft. How much work is required
10. physics

A 60 kg worker pulls buckets of sand from height of 10 m using a pulley fixed to a wooden beam.While he is pulling a 20 kg bucket filled with sand he slips and falls down holding the rope.Assuming that the worker did not collide with …

More Similar Questions