7. If a hot spoon is placed in a glass of cold
1 answer:
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Answer:
4.44 kN in the opposite direction of acceleration.
Explanation:
Given that, the initial speed of the car is,
And the mass of the car is,
The total distance covered by the car before stop,
And the final speed of the car is,
Now initial kinetic energy is,
Substitute the value of u and m in the above equation, we get
Now final kinetic energy is,
Substitute the value of v and m in the above equation, we get
Now applying work energy theorem.
Work done= change in kinetic energy
Therefore,
Here, the force is negative because the force and acceleration in the opposite direction.
Answer:
-0.9045 j
Explanation:
Here K= 270 N/m
distance 1 = 4.60 mm=0.0046 m
when pen is compressed ;
distance 2 = 6.70 mm + distance1 = 0.0067 m+0.0046 m= 0.0113 m
The pen store in itself two types of PE
Which is Initial PEi = 1/2 ×K× [ =0.5×270×0.0046 =0.621 j
and Final PEf = 1/2 × K × = 0.5×270×0.0113=1.5255 j
When the pen gets ready - it goes ahead distance d2 and is then pressed back distance d1 for writing.
Total PE when ready = 0.621-1.5255= - 0.9045 j
so, work = -0.9045 j