What is the work done on the block by the worker and weight forces?

In summary, a 36 kg block of ice slides down a frictionless incline with a length of 1.2 m and a height of 0.48 m. A worker exerts a force on the block, parallel to the incline, to keep it moving at a constant speed. The magnitude of the force exerted by the worker is 141.2629 N. The work done on the block by the worker's force is -141.2629 J, and the work done on the block by its weight is 141.2629 J. The work done is equal to the change in kinetic energy, and the distance traveled by the block along the direction of the worker's force is not exactly 1 m
  • #1
ViewtifulBeau
50
0
A 36 kg block of ice slides down a frictionless incline 1.2 m long and 0.48 m high. A worker pushes up against the ice, parallel to the incline, so that the block slides down at constant speed.
(a) Find the magnitude of the force exerted by the worker.
(b) Find the work done on the block by the workers force.
(c) Find the work done on the block by the weight of the block.

I found the answer to (a) by sin(arcsin(.48/1.2)) * 9.81 * 36 kg which is 141.2629.
I don't know what to do for (b) and (c). My first guess would be that (b) is -141.2629 and (c) is 141.2629. But I am not sure.
 
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  • #2
Work is equal to the change in kinetic energy. If I push on the wall, am I doing work on the wall?


By the way, a) is correcct, but I don't think it's absolutely necessary to take the sin of the arcsin.
 
  • #3
Work done BY a Force is F dot displacement .
You know F_by_worker is up-the-ramp, so does neg. W,
but how far does the block travel along that direction?
[ hint: not exactly 1 meter ! ]

(mg acts along the -.48 m Delta_z, so does +'ve W)
 

FAQ: What is the work done on the block by the worker and weight forces?

1. How does the angle of the incline affect the speed of ice sliding?

As the angle of the incline increases, the speed of ice sliding also increases. This is due to the force of gravity pulling the ice down the incline at a steeper angle, resulting in a greater acceleration and therefore, a higher speed.

2. Is friction a factor in ice sliding on an incline?

Yes, friction plays a significant role in the speed and motion of ice sliding on an incline. Friction is the force that resists the motion of the ice and is affected by factors such as the texture of the ice and the angle of the incline.

3. Can the weight of the ice affect its sliding speed on an incline?

Yes, the weight of the ice can impact its sliding speed on an incline. Heavier ice will have a greater force of gravity acting on it, resulting in a faster acceleration and therefore, a higher speed.

4. How does the surface of the incline affect ice sliding?

The surface of the incline can greatly impact the speed and motion of ice sliding. A smoother surface will result in less friction, allowing the ice to slide faster. However, a rougher surface may slow down the ice due to increased friction.

5. What other factors can affect the speed of ice sliding on an incline?

Aside from the angle, weight, and surface of the incline, other factors such as temperature, wind, and the presence of obstacles can also affect the speed of ice sliding. Warmer temperatures can melt the ice, making it slide slower, while wind can either assist or resist the motion of the ice. Obstacles on the incline can also alter the path and speed of the ice sliding.

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