How many prime mover is needed to pull the crane with velocity 10m/min?

In summary: The correct equation is P = F * v, where F is the force in Newtons and v is the velocity in m/s. Therefore, the power required to overcome friction is 120,000 kg * 9.81 m/s^2 * 0.17 m/s = 200340 watts. Since 1 prime mover unit is 164,120 watts, the total number of units needed to overcome friction would be 200340/164120 = 1.22 units. However, since the crane also needs to be accelerated, the total number of prime mover units needed would be greater than 1.22 units, but less than 10 units. In summary, to pull a 2000 tonne crane
  • #1
ainaz89
2
0

Homework Statement



prime mover = 220 hp
crane = 2000 tonne
velocity crane = 10m/min = 0.17m/sec
acceleration crane = 0.017m/sec
every 100 tonne = 6 tonne of friction

1hp = 726 W
1 tonne = 1000 kg

Homework Equations



how many prime mover are needed to pull the crane?prime mover 220 hp = 164120W

for every 100 tonne = 6 tonne of friction
2000tonne = 120 tonne of friction

m = 2000tonne - 120 tonne = 1880 tonne

P = F*v
= mg * v
= (1880*1000)(9.81)*(0.17)
= 3135276W

so, total of PM = 3135276/164120
= 19 units.

the answer should be less than 10 units.
 
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  • #2
I need some clarification for this problem. Can I assume that the crane accelerates from rest to a final velocity of .17 m/s at an acceleration of .017 m/s^2? Friction forces are in Newtons not Kg (or tonne). Is 120 tonne friction 120,000 Kg * 9.8 M/s^2= 1.18 x 10^6 Newtons? 1 prime mover unit is 164,120 watts?
 
  • #3
RTW69: yes..the acceleration of the crane is 0.017m/s^2.and u can change the parameters into SI unit.as i calculated, the prime mover power is 164120 watts.
 
  • #4
OK, there are two parts to this problem. Part 1 is how much power is required to get the crane from rest to a final velocity given the acceleration. You need to do a free body diagram oft he accelerating crane, sum of the forces in x-direction=M*a. Use your one-dimensional motion equations to find distance and time for crane to reach final velocity. Power= F*D/t

The second part of the problem is how much power is required to keep the crane moving at final velocity. There is no acceleration so sum of forces in x-direction=0. The motor just needs to overcome the friction forces. Power=F*Vel. Which power requirement is larger, part 1 or part 2? convert larger to power units.

Your P=F*V equation is incorrect
 
  • #5


Based on the given information, it seems that the crane would require at least 19 units of the prime mover to pull it with a velocity of 10m/min. However, this number may vary depending on the efficiency and power of the prime mover and the specific details of the crane's design and operation. It is also important to consider the safety and stability of the crane while it is in motion. Further analysis and calculations may be needed to determine the exact number of prime movers required for this scenario.
 

1. How does the velocity of the crane affect the number of prime movers needed?

The velocity of the crane does not have a direct impact on the number of prime movers needed. The number of prime movers required is determined by the weight of the crane and the load it is carrying.

2. Can a single prime mover pull the crane with a velocity of 10m/min?

It depends on the weight of the crane and the load it is carrying. In some cases, a single prime mover may be able to pull the crane with a velocity of 10m/min, but in most cases, multiple prime movers will be required for safety and efficiency.

3. What is the maximum velocity a prime mover can pull the crane?

The maximum velocity a prime mover can pull the crane depends on the weight and load of the crane, as well as the power and capabilities of the prime mover. It is important to consult with a professional engineer to determine the maximum safe velocity for a specific crane and prime mover combination.

4. How do the terrain and weather conditions affect the number of prime movers needed?

The terrain and weather conditions can have a significant impact on the number of prime movers needed. For example, if the terrain is rough or hilly, more prime movers may be required to pull the crane. Similarly, if there are adverse weather conditions such as strong winds, additional prime movers may be needed to ensure safe and stable operation of the crane.

5. Are there any safety considerations when determining the number of prime movers needed?

Yes, safety is a crucial factor when determining the number of prime movers needed to pull a crane. It is important to ensure that the number of prime movers is sufficient to handle the weight and load of the crane, as well as any external factors such as terrain and weather conditions. Consulting with a professional engineer and following all safety guidelines and regulations is essential for the safe operation of the crane and prime movers.

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