Simple Machines B/Compound Machines C Question Marathon

[SWAnG]

Swagg used a force of 20.0N to turn a crank handle of radius 0.400m that rotated an axle of radius 0.100m, so Swagg could raise a 60.0N bucket of water.
a) What is the ideal mechanical advantage of the wheel?
b) What is the actual mechanical advantage of the wheel?
c) What is the efficiency of the wheel?

[chinesesushi]

Swagg used a force of 20.0N to turn a crank handle of radius 0.400m that rotated an axle of radius 0.100m, so Swagg could raise a 60.0N bucket of water.
a) What is the ideal mechanical advantage of the wheel?
b) What is the actual mechanical advantage of the wheel?
c) What is the efficiency of the wheel?

4
3
0.75 or 75%

[misterstealyogirl]

Derp lifts a 50N object 10 meters and walks forward 50 meters. How much work did Derp do on the mass?

[misterstealyogirl]

How do you calculate torque?

[SWAnG]

Derp lifts a 50N object 10 meters and walks forward 50 meters. How much work did Derp do on the mass?

500 N*m

[SWAnG]

How do you calculate torque?

The cross product of the displacement and force vector

[chinesesushi]

Derp lifts a 50N object 10 meters and walks forward 50 meters. How much work did Derp do on the mass?

Not sure if right... (Click to Show Hidden Text)

W = 50 N * 10 m + 50 N * 50 m = 3000 N*m

And torque is Fd where F is the force applied and d is the distance from pivot point.

[misterstealyogirl]

Derp lifts a 50N object 10 meters and walks forward 50 meters. How much work did Derp do on the mass?

Not sure if right... (Click to Show Hidden Text)

W = 50 N * 10 m + 50 N * 50 m = 3000 N*m

And torque is Fd where F is the force applied and d is the distance from pivot point.

What I think (Click to Show Hidden Text)

I'm don't think Derp does any work when he walks forward 50 meters. W=change in energy and the object's energy doesn't change when he walks forward.

[Sciolapedia]

Derp lifts a 50N object 10 meters and walks forward 50 meters. How much work did Derp do on the mass?

Not sure if right... (Click to Show Hidden Text)

W = 50 N * 10 m + 50 N * 50 m = 3000 N*m

And torque is Fd where F is the force applied and d is the distance from pivot point.

What I think (Click to Show Hidden Text)

I'm don't think Derp does any work when he walks forward 50 meters. W=change in energy and the object's energy doesn't change when he walks forward.

Work=force times distance.Its not about the objects energy but rather about the work that Derp does. Although hes not moving anything up, hes still moving it so the distance part is fulfilled and he is definitely exerting a force. So part 2 of the walk still has force.

That is why i agree with 3000 joules cuz part 1 has 500 and part 2 has 2500.

[SWAnG]

But the objects force is in relation to the acceleration of gravity. That is the only force being exerted on the object no? Him moving isn't really him exerting force on the object.