a machine uses a force of 250 newtons to move an object 20 meter in 5 seconds. What is the power of the machine?
1 answer:
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The Correct choice is ~
D. 18.0 Newtons
because the resultant force can't exceed 16 Newtons ~
Apply the law of conservation of momentum for this situation. The law states that the momentum of a system is constant (in absence of external forces acting on it).
The 'system' in this case are the two skaters. There is no external force on the skaters. Suppose the skaters are initially standing still. The momentum in the system is 0. This value will need to remain constant, even after the mutual push (which is a set of forces from <em>inside</em> the system). So we know that
(total momentum before) = (total momentum after)
Indexing the masses and velocities by the first letter of the skaters' names:
From the last row, you can see that the skaters will have momentum of same magnitude but opposite direction, after the push off. That answers the first question: neither will have a greater momentum (both will have one of same magnitude).
Since Ricardo is heavier, from the above equality it follows that
In words, Paula has the greater speed, after the push-off.
Answer:
2 m/s².
Explanation:
The forces acting on the crate have been shown in the figure below.
Net force acting on the crate in the horizontal direction = 400 - 250 = 150 N towards right.
For the forces of vertical direction we can write,
Normal force = 150 + Mg = 150 + 250 = 400 N (here g = 10 m/s² have been taken)
The magnitude of frictional force that will act on the crate = μ × Normal force
So, Frictional force = 0.25 × 400 = 100 N
Thus, the net force that will cause acceleration in the crate will be
Force in the right direction - frictional force
= 150 - 100 = 50 N
As we know,
Acceleration = =
= 2 m/s²
So, the net acceleration in the crate will be 2 m/s².
