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The potential energy due to a force is given by:
       \(U(x,y)= -3xy+2y^2\) (in joule)
where \(x,y\) are in metres.
The force acting when \(x=0,y=1\) (m) is: (in magnitude)
1. \(2~\text{N}\)
2. \(1~\text{N}\)
3. \(3~\text{N}\)
4. \(5~\text{N}\)

Subtopic:  Potential Energy: Relation with Force |
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The force acting on a particle is shown in the diagram as a function of \(x\). Work done by this force when the particle moves from \(x=0~\text{to}~x=2~\text{m}\) equals:

1. \(5~\text{J}\) 2. \(10~\text{J}\)
3. \(7.5~\text{J}\) 4. \(2.5~\text{J}\)
Subtopic:  Work Done by Variable Force |
 57%
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A simple pendulum consisting of a bob of mass \(m\), and a string of length \(L\) is given a horizontal speed \(u\), at its lowest point as shown in the figure. As a result, it rises to \(B\), where it just comes to rest momentarily with \(OB\) horizontal.
During the motion \(AB,\)

          

1. Work done by the string is zero
2. Work done by gravity is \(-mgL\)
3. Change in K.E. of the bob is \(-\dfrac{1}{2}mu^2\)
4. All the above are true
Subtopic:  Work Energy Theorem |
 89%
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A person of mass \(m\) ascends the stairs and goes up slowly through a height \(h\). Then,

1. Work done by gravity is \(mgh\)
2. Work done by normal reaction is \(mgh\)
3. Work done by normal reaction is zero
4. Work done by gravity is stored as gravitational \(P.E\).
Subtopic:  Concept of Work |
 54%
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A particle of mass '\(m\)' is released from the origin, and it moves under the action of a force: \(F(x)= F_0-kx\)
The maximum speed of the particle is, \(v= \)

1. \(\sqrt{\dfrac{F_0^2}{mk}}\) 2. \(\sqrt{\dfrac{2F_0^2}{mk}}\)
3. \(\sqrt{\dfrac{F_0^2}{2mk}}\) 4. \(2\sqrt{\dfrac{F_0^2}{mk}}\)
Subtopic:  Work Energy Theorem |
 51%
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A projectile is launched from a cliff of height \(h,\) with an initial speed \(u,\) at an angle \(\theta.\) The speed with which it hits the ground:

1. depends on the vertical component, \(u \text{sin}\theta\)
2. depends on the horizontal component, \(u \text{cos}\theta\)
3. depends on \(u,\) but not on \(\theta\)
4. depends on the quantity \(u \text{tan}\theta\)
Subtopic:  Work Energy Theorem |
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A small block of mass '\(m\)' is placed against a compressed spring, of spring constant \(k\). The initial compression in the spring is '\(d\)'. The block is released and the spring relaxes, while the block is projected up to a height \(H\) relative to its initial position. Then, \(H\) =
   

1. \(\dfrac{kd^2}{2mg}\) 2. \(\dfrac{kd^2}{2mg}+d\)
3. \(\dfrac{kd^2}{2mg}-d\) 4. \(\dfrac{kd^2}{mg}+d\)
Subtopic:  Elastic Potential Energy |
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Given below are two statements: 

Assertion (A): The net work done by gravity is equal to the loss in the vertical component of the kinetic energy for a projectile.
Reason (R): The work-energy theorem applies to all systems including projectiles.
 
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. (A) is False but (R) is True.
Subtopic:  Work Energy Theorem |
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The minimum speed that a simple pendulum's bob should be given so that it rises to a level where its string makes \(60^\circ\) with the vertical is:

1. \(\sqrt{2gL}\)
2. \(\sqrt{2gL}\) \(\text{cos} 60^\circ\)
3. \(\sqrt{2g(L-L~\text{cos}60^\circ)}\)
4. \(\sqrt{2gL}\) \(\text{sin} 60^\circ\)
Subtopic:  Gravitational Potential Energy |
 83%
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The net work done by all forces (internal and external) equals the change in:

1. potential energy
2. kinetic energy
3. total energy
4. kinetic energy and conservative potential energy

Subtopic:  Work Energy Theorem |
 68%
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