Answer:
Explanation:
Work done in lifting the weight once = mgh
= 20 x 9.8 x (1.9+1.7)
= 705.6 J
= 705.6 / 4.2 calorie
= 168 cals
Total energy to be spent = 600 x 10³ cals
No of times weight is required to be lifted
= 600 x 10³ / 168
= 3.57 x 10³ times
Total time to be taken = 2 x 3.57 x 10³
= 7.14 x 10³ s
=119 minutes .
I believe the answer is x
Mechanical efficiency is a measure of how well the machine converts the input work or energy into some useful output. It is calculated by dividing the output work by the input work. The ideal machine has mechanical efficiency equal to unity, while the real machine has mechanical efficiency less than unity
Answer:
No
Explanation:
constant velocity means zero acceleration because acceleration is rate of change of velocity. So when velocity remains constant there would be no acceleration.
in case of constant acceleration it means that velocity changes but with some consistent (same) amount each time. For example some object falling from tower, Velocity of the object will change(increases) by 9.8m/s for each second due to gravity of Earth. In this case there is change in velocity each second but with some consistent amount that is 9.8m/s.
