Potential Energy

Q. In a conservative field, the potential energy U as a function of position x is given by U = x2. Then the corresponding conservative force is given by Options:a- x b-2x c- –x d-–2x

Q.

Energy needed in breaking a drop of radius R into n drops of radii r is given by

1. 

2. 

3. 

4. 

Q. A bolt of mass 0.3 kg falls from the ceiling of an elevator moving down with an uniform speed of 7 m s¯¹. It hits the floor of the elevator (length of the elevator = 3 m) and does not rebound. What is the heat produced by the impact ? Would your answer be different if the elevator were stationary ?

Q. A body of mass 2 kg s projected vertically upwith velocity of 20 m/s. If the energy spent in overcoming air resistance is 100 J, the maximumheight attained by it is (g 10 m/s2)(1) 15 m(2) 20 m(4) 25 m3) 10 m

Q. the change in potential energy when a body of mass m is raised to height nR from the earths surface is (R is radius of earth)

Q. 12. A body falls freely under gravity. Its velocity is V, when it has lost potential energy equal to U. What is the mass of the body

Q. The eccentricity of the earths orbit is e The ratio of itsmaximum speed in its orbit to its minimum speed is:

Q. A ball of mass 7.2 kg is launched from the Earths surface to a circular orbit at a height of 350 km from the surface. In doing so, what is the change in mechanical energy of the ball? (A) 250MJ (B) 317MJ (C) 213MJ (D) zero

Q. a rope of length l and massm is connected to a chain of length l and mass 2m and hung vertically .what is the change in gravitational potential energy if the system is inverted and hung from the same point(rope on upper part in first situation)

Q. if potential energy of a body of mass m on the surface of earth is taken as 0 the P.E. at a height h above surface of earth is

Q. what is the formula for potential energy and powers formula

Q. 28.A ball is projected vertically upwards with a certain initial speed. Another ball of same mass is projected at an angle 60 with the vertical with the same initial speed. At highest points of their journey, the ratio of their potential energies will be- (a)1:1 (b)2:1 (c)3:2 (d)4:1

Q. 96. Show that if a body be projected vertically upward from the surface of the earth so as to reach a height nR above the surface i) the increase in its potential energy is (n/n+1)mgR ii) the velocity with which it must be projected is \sqrt{}(2ngR/n+1), where R is the radius of the earth and m the mass of body

Q. A car of mass 1500 kg is moving with a velocity of 60 km\h. The work done by its brakes to bring it to rest is?

Q. Two particles of equal masses moving with same speed collide perfectly in-elastically. After the collision, the combined mass moves with half of the speed of the individual masses. The angle between the initial momenta of individual particle is .

1. ${60}^{\circ }$
2. ${90}^{\circ }$
3. ${120}^{\circ }$
4. ${45}^{\circ }$

Q.

A liquid of density d is pumped by a pump p from situation (i) to situation (ii) as shown in the diagram. If the cross-section of each of the vessels is a, then the work done in pumping (neglecting friction effects) is

1. 

2. 

3. 

4. 

Q. 90A body of mass m is projected from ground with speed u and angle theta with the horizontal. Power delivered by gravity to it at half of maximum height from ground is ?

Q. a beaker containing water at 373 k is respresentingan open system , is placed in the room. predict the nature of work done

Q. The potential energy of a body of mass 2kg is given as U=3x+4y.The magnitude of accelerationif the body is?

Q. 91. A person is holding a bucket by applying a force of 10N. He moves a horizontal distance of 5m and then climbs up a vertical distance of 10m. Find the total work done by him.

Q. why object gains potential energy when kept at height but has no potential energy energy when kept at ground

Q. A 0.5Kg of ball is thrown up with an initial speed of 14m/s and reaches a maximum height of8.0m. How much energy is dissipated by air drag acting on balll durng the ascent? (1)19.6J (2)4.9J (3)10J (4)9.8J

Q. Why restoring force is zero at mean position even if there is some potential energy possessed by the particle?

Q.

If the momentum of an object is increased by $10\%$ then its kinetic energy will increase by

1. $20\%$

2. $21\%$

3. $40\%$

4. $19\%$

Q. 118.A uniform chain of length L and mass M lying on a smooth table and one third of its length is hanging vertically down over the edge of table . if g is acceleration due to gravity, the minimum work required to pull the hanging part of the chain on the table is

Q. A labour carries 10 sacks of cement of 25 kg each one by one on the third floor of a building with five identical floors (1 ground floor and 4 floors). If height of the building is 100 m, the work done by the labour against gravity in carrying the sacks of cement is (take g =10m/s^2)

Q. Potential energy of certain spring when strechedthrough x distance is 10 J. Amount of workdone onthis spring to stretch it through a distance 2xwill be

Q. A body of mass $m$ is taken from surface of earth to height of $5R$. If gravity at surface is $g_o$, then work done by external force to move the body is (neglect air resistance)

1. $5m{g}_{0}R$
2. $\frac{m{g}_{0}R}{6}$
3. $\frac{5m{g}_{0}R}{4}$
4. $\frac{5m{g}_{0}R}{6}$

Q. When a conservative force does positive work on a body, then the (1) Potential energy of body increases (2) Potential energy of body decreases (3) Total mechanical energy of body increases (4) Total mechanical energy of body decreases

Q. A STONE OF MASS 10GRAMS IS THROWN VERTICALLY UPWARDS.ITS MINIMUM AND MAXIMUM DISTANCE FROM A FIXED POINT A IS 6METRES AND 6ROOT5METRES RESPECTIVELY. WHEN THE STONE IS AT THE MAXIMUM HEIGHT IT IS AT A DISTANCE 10METRES FROM POINT A. FIND THE INITIAL KINETIC ENERGY OF THE BALL