# Physics

posted by cake

Fig.19 shows a crane lifting a car of mass 850 kg at constant velocity through a height of 12m in a time of 40s. The crane has a working efficiency of 60%.
i) Calculate the tension in the lifting cable (in N)
ii) Calculate the total input power required by the crane to lift the car (in W)
iii) Suggest and explain many ways the crane can be modified to improve its efficiency

1. Henry

I. F = M*g = 850 * 9.8 = 8330 N. = Tension in the cable.

II. Po = F*d/t = 8330 * 12/40 = 2499 J./s = 2499 Watts. = Power out.

Pin = Po/Eff. = 2499/0.60 = 4165 Watts.
= Input power.

2. cake

Henry what are the equations you used fully written out in words as the abbreviations used are different in my school so please tell me the full words please

3. Henry

I will give you the meaning of the abbreviations, but you will have to write them into the equations.

F = Force in newtons.

2. M = Mass in kilograms.

3. g = Acceleration due to gravity in m/s^2.

4. d = Distance in meters.

5. J = Joules.

6. s = Time in seconds.

7. Pin = Power input.

8. Eff. = Efficiency.

## Similar Questions

1. ### physics

A moto of a crane is lifting a 100 kg load 20m high using 25 kj of electrical energy. calculate the efficiency
2. ### physics

A crane lifts a concrete hopper of mass 370 kg from the ground to the top of a 38 m building that is under construction. The hopper moves with a constant speed during the lift. The power rating of the crane motor is 8.2 kiloWatts. …
3. ### Acc

A crane with the mass of 500kg,lifting an object of the mass of 50kg, what wil be the gravitational potential energy of a crane?
4. ### Cranes

08/09/2005 Physics A crane is lifting a 200 pound object. The crane boom is 50 ft long. The boom forms an 85 degree angle with the horizontal. What is the torque applied to the crane boom?
5. ### Physics

A crane is lifting a 500kg payload straight up at a constant speed of 0.7ms-1. (a)What is the power output of the crane. (ignoring losses)?
6. ### Physics

crane lifts a 75 kg girder 8.85 m. How much work does the crane do lifting with an upward acceleration of 1.20 m/s ^2?
7. ### physics

3 Fig. 3.1 shows the arm of a crane when it is lifting a heavy box. Fig. 3.1 (a) By the use of a scale diagram (not calculation) of the forces acting at P, find the weight of the box. [5]
8. ### Physics Help

A crane is used to lift air conditioning units to the top of a 5-story building. Each story is 3.5 m high. The crane accelerates the units while lifting the units past the first story and then lifts them at a constant velocity past …
9. ### Physics Help Urgent Please!!!

A crane is used to lift air conditioning units to the top of a 5-story building. Each story is 3.5 m high. The crane accelerates the units while lifting the units past the first story and then lifts them at a constant velocity past …
10. ### algebra (check work)

a camera car with a crane is used to film a movie. the crane's max. height is 18ft and the min. height is 4ft. write a compound inequality that describes the possible heights of the crane. 18≥x≤4

More Similar Questions