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Solution 71
Work done is more on the bicycle because the truck does not move at all and the bicycle moves through a certain distance. And work is said to be done only when applied force produces motion in the body.
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Solution 72
The work done will decrease as the angle between the direction of force and direction of motion is increased gradually because
W= F cos θ
and cos θ decreases as the angle θ is increased.
Solution 73
The work done will be zero when
Solution 75
The work done is zero because the gravitational force acts along the radius of the circular path, at right angles i.e. 90^{o} to the motion of
Solution 76
Weight of man = Mg = 800 N
Weight of package = mg = 200 N
Total weight of man and package = Mg + mg = (M+m)g = 1000 N
Height of the summit, h = 1200 m
i) Work done = (M+m) x g x h = 1000 x 1200 = 12 x 10^{5} J
ii) Potential energy of the package = m x g x h = 200 x 1200 = 2.4 x 10^{5} J
Solution 77
Potential energy becomes maximum.
Solution 78
The work done by both X and Y are equal because irrespective of whether they reach the top of
Solution 79
Yes, the kinetic energy of the ball thrown inside a moving bus depends on the
speed of the bus because the speed of the bus adds up to the speed with which
the ball is thrown inside the moving bus.
Solution 80
distance covered before stopping , s = 20 cm = 0.2 m
Here, initial velocity u = 400m/s
Final velocity = 0
1 videos228 docs21 tests

1. What is work in the context of physics? 
2. How is work related to energy? 
3. What is the unit of work and energy? 
4. How can one calculate the work done in lifting an object vertically? 
5. Can the work done on an object be negative? 
1 videos228 docs21 tests


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