Energy

Q.

A wind-powered generator converts wind energy into electrical energy. Assume that the generator converts a fixed fraction of the wind energy intercepted by its blades into electrical energy. For wind speed v, the electrical power output will be proportional to

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Q. 33. A particle is released from a height S. At certain height its kinetic energy is three times its potential energy. The height and speed of the particle at that instant are respectively

Q.

The gravitational field in a region is given by $\overline{E}=\left(10N/kg\right)(\overline{i}+\overline{j})$. The work done by an external agent to slowly shift a particle of mass 2 kg from the point (0, 0) to a point (5 m, 4 m) is..

1. 100J

2. ZERO

3. 60J

4. 180J

Q.

Deep water runs almost still. What does it explain?

1. Surface energy

2. Equation of continuity

3. Magnus effect

4. Bernoulli's Theorem

Q. a 10 metric ton truck drives up a hilly road of gradient 1 in 50 at a speed of 36 km/h if the coefficient of kinetic friction between the road and tyres is 0.2 find the power delivered by the engine

Q. F= K(xi+yj) is working on a particle which moves from (0, 0) to (a, 0) along yaxis. Find work done by the forc.

Q. 64.If the units of length, mass and time are doubled, what will be the change in work?

Q. 41.A father racing with his son, has one third kinetic energy of the son, who has one-third mass of the father. The father speeds up by 2m/s and then has same kinetic energy as that of the son. The initial speeds of the father and the son are (1) (_/3+1), 3(_/3+1) (2) (_/2+1), 3(_/2+1) (3) [1/(_/3+1)], [3/(_/3+1)] (4) [1/(_/2+1)], [3/(_/2+1)]

Q. 20. A boy is standing on a horizontal massless rotating wheel with his hands stretched. Kinetic energy of boy is 120 J. If he now folded his hands then M.I is reduced to 80%. Then a new K.E. of boy, (1) Increases by 30 J (2) Decreases by 30 J (3) Increases by 20 J (4) Remains constant

Q.

The r.m.s speed of oxygen at NTP is x m/s. If the gas is heated at constant pressure till its volume is four fold, what will be its final temperature and r.m.s speed?

1. 2184 K, 8x m/s

2. 3276 K, 3x m/s

3. 1092 K, 2x m/s

4. 4368 K, 4x m/s

Q. 18. two masses in the ratio of 1:4 have their speeds in the ratio of 4:5 find the ratio of their kinetic energy

Q. ntan athlete takes 100g of glucose of energy equivalent to 1560 KJ. how much amount of energy is uptaken by 1g molecule of glucosen

Q. In a practical unit if the unit of mass becomesdouble and that of unit of time becomes half, then8 joule will be equal to .unit of work.(2) 4(4) 10(3) 1

Q. what is the velocity at which its kinetic energy is equals to its rest mass energy ?

Q. 39. One mole of water vapourises against 1atm pressure and 373K temperature then calculate work done (assume ideal behaviour of water vapour) (1)3157 joule (2)3090 joule (3)zero (4)information incomplete.

Q. 40. A truck pulls a mass of 1200 kilogram at constant speed of 10 metre per second on a level road the tension in coupling is 1000 Newton what is the power spent on the Mass. find tension when truck moved up Road with information 1 in 6

Q. A particle is released from height $S$ from the surface of the Earth. At a certain height, its kinetic energy is three times of its potential energy. The height from the surface of earth and the speed of the particle at that instant are respectively

1. $\frac{S}{2},\frac{\sqrt{3gS}}{2}$
2. $\frac{S}{4},\sqrt{\frac{3gS}{2}}$
3. $\frac{S}{4},\frac{\sqrt{gS}}{2}$
4. $\frac{S}{4},\sqrt{3gS}$

Q.

A metal rod, fixed at both ends, has a length $l$, area of cross section $A$ and youngs modulus $Y$ and coefficient of linear expansion $\alpha$ is heated through $t^{0}C$. The work done in heating the rod is

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Q.

The ——— of a charged body determines the direction of flow of charge.

Q. A uniform metal rod of $4{\text{mm}}^2$ cross-section is heated from $0^{\circ }\text{C}$ to ${40}^{\circ }\text{C}$. The coefficient of linear expansion of the rod is $2\times {10}^{-6}/{}^{\circ }\text{C},Y={10}^{11}{\text{N/m}}^2$. The energy stored per unit volume of the rod is

1. $1440{\text{J/m}}^3$
2. $320{\text{J/m}}^3$
3. $2880{\text{J/m}}^3$
4. $5760{\text{J/m}}^3$.

Q.

Answer carefully, with reasons:

(a) In an elastic collision of two billiard balls, is the total kinetic energy conserved during the short time of collision of the balls (i.e. when they are in contact)?

(b) Is the total linear momentum conserved during the short time of an elastic collision of two balls?

(c) What are the answers to (a) and (b) for an inelastic collision?

(d) If the potential energy of two billiard balls depends only on the separation distance between their centres, is the collision elastic or inelastic? (Note, we are talking here of potential energy corresponding to the force during collision, not gravitational potential energy).

Q.

A black body at a temperature of ${227}^0$C radiates heat energy at the rate of 5 cal/$c{m}^2$-sec. At a temperature of ${727}^0$C, the rate of heat radiated per unit area in cal/$c{m}^2$ will be

1. 80

2. 250

3. 500

4. 160

Q. N-m/sec is unit of ? a.work b.pressure c.power d.energy

Q.

1calorie = ?

1. 414.8 Joules

2. 4148 Joules

3. 4.148 Joules

4. 41.48 Joules

Q. Ques: A drop of mercury of radius R is split into N identical droplets. Calculate the Surface energy released. (Given S is the surface tension).

Q.

A particle of mass 10 gm is describing S.H.M. along a straight line with period of 2 sec and amplitude of 10 cm. Its kinetic energy when it is at 5 cm from its equilibrium position is

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Q. The constant in an expression for a physical quantity can be accurately derived from dimensional analysis

1. False
2. True

Q. 89.A boy, his mother and father have their masses in the respective ratio 1:2:3. Find the ratio of their speeds at which they should run so as to have the same kinetic energy for each of them with respect to ground?

Q. a body moving along a circular path with uniform speed covers a distance of 20m. if the centripetal force acting on it is 10N, what is work done by force?

Q. A $2\text{g}$ bullet moving with a speed of $210\text{m/s}$ brought to a sudden stoppage by an obstacle. The total heat produced goes to the bullet. If the specific heat of the bullet is $0.03{\text{cal/g}}^{\circ }\text{C}$ the rise in its temperature will be

1. ${175}^{\circ }\text{C}$
2. ${180}^{\circ }\text{C}$
3. ${150}^{\circ }\text{C}$
4. ${125}^{\circ }\text{C}$