Determine the stiffness of the spring to hold the 85-kg crate in the position shown.
1 answer:
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Answer:
<em>The work is 750 J</em>
<em>The power is 37.5 watt</em>
Explanation:
<u>Mechanical Work and Power</u>
Mechanical work is the amount of energy transferred by a force. It's a scalar quantity, with SI units of joules.
Being the force vector and
the displacement vector, the work is calculated as:
If both the force and displacement are parallel, then we can use the equivalent scalar formula:
W=F.s
Power is the amount of energy transferred or converted per unit of time. In the SI, the unit of power is the watt, equal to one joule per second.
The power can be calculated as:
Where W is the work and t is the time.
a)
The table is pushed d=15 m across a room with a force F=50 N, thus the work is:
W=50 * 15 = 750 J
The work is 750 J
b)
The time needed to push the table is t=20 seconds, thus:
The power is 37.5 watt