Rita jeptoo of kenya was the first female finisher in the 110th boston marathon. she ran the first 10.0 km in a time of 0.5689 h
1 answer:
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Answer:
The Amount of work is done on the box by the net force is 378 Joules.
Explanation:
Given:
A 42 N net force is applied to a box which slides horizontally across a floor.
Force = 42 N
Force applied for a displacement of 9.0 m
Displacement = 9.0 m
To Find:
Amount of work is done on the box by the net force = ?
i.e Work = ?
Solution:
When a force causes a object to move, work is being done on the object by the force. Work is the measure of energy transfer when a force (F) moves an object through a distance (d).
Formula is given by
Substituting the given values we get
∴ Work = 42 × 9.0
∴ Work = 378 N-m
or
∴ Work = 378 Joules
The Amount of work is done on the box by the net force is 378 Joules.
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.