Work, power, pulleys, levers and ramps homework

[Nikki196]

I have a few questions I've been having troubles with, and I was hoping someone could help me out...
1) A machine does 4000 J of work in accelerating a 20 kg object, intially at rest, at 3.0 m/s2 for 5.0s determine
a) The efficiency of the machine
b) The power output of the machine

2)A block and tackle is used to raise a 100kg load. If the maximum applied force is 220N, how many strands of rope must support the moveable block?

3)A wrench is used to turn a bolt of 6.0mm diameter. The centre of the bolt head is 0.2m from the applied force.
a) what is the IMA of this machine?
b) If the efficiency is 50%, what is the AMA of the machine?

4) A ramp is 12m in length and has a grade of 25%
a)If friction is neglected, what force is required to push a 120-kg box up the ramp?
b) If the actual force required is 490 N, determine the efficiency of the ramp.

If someone could help me it would be awesome!
Nikki196

 

[Mk]

Well I did this in 7th grade, what do you know so far about these problems? We wouldn't want to do your homework for you, would we?

 

[Mk]

IMA

IMA = D_E/D_R
where D_E equals the effort distance and D_R equals the resistance distance.

Properties of an ideal machine, which does not exist in reality:
1. It is frictionless.
2. Its actual mechanical advantage is equal to its ideal mechanical advantage.
3. Its mechanical efficiency is 100%

Power

P=W/t
P=power
W=work
t=time

Power is work exerted over time.

 

[Doc Al]

Please do not double post!

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