Average and Instaneous Power

Q. coversion of 1 Mw power on a new system having basic unit mass , length and time as 10 kg , 1 dm and 1minute respectively is

Q.

A particle moves with a velocity $\overrightarrow{v}=5\hat{i}-3\hat{j}+6\hat{k}m{s}^{-1}$ under the influence of a constant force $\overrightarrow{F}=10\hat{i}+10\hat{j}+20\hat{k}N$ . The instantaneous power applied to the particle is

1. 

2. 

3. 

4. 

Q.

A particle of mass $0.2kg$ is moving in one dimension under a force that delivers a constant power $0.5w$ to the particle. If the initial speed $\left(inm{s}^{-1}\right)$ of the particle is zero, then the speed $\left(inm{s}^{-1}\right)$ after $5s$ is

1. $4$

2. $2$

3. $1$

4. $5$

Q. A body of mass m accelerates uniformly from rest to a speed v0 in time t0. The work done on the body till any time t is

Q. 65. A bullet of mass 10g leaves a riffle at an initial velocity of 1000m/s and strike the earth at the same level with a velocity of 500m/s.the work done in joules overcoming the resistance of air will be?

Q. A body whose mass is 2 kg initially at rest. A cons†an t force of 5 N acts on it for 10 seconds. Then the average power is?

Q. The velocity of a particle of mass 2 kg moving along x-axis is given by v=2\sqrt x (where v is in m/s and x is in m). The work done by the force acting on the particle during its motion from x=2 m to x4=m is

Q. 18. The work done required to stop a car of mass 1000kg moving at a velocity of 20m/s will be

Q. An automobile of mass m accelerates, starting from rest, with the engine supplying constant power 'P'. How the velocity of the automobile vary with time?

1. 

2. 

3. 

4. independent of 't'

Q. Q:- A car of mass 2000 kg travelling with a uniform velocity of 2m/s accelerates till its velocity becomes 22m/s. The work done on the car is- 1. 480 kJ 2. 48 k

Q. 4. Which of the following expressions has the same unit as power: A force x velocity B work x time C forcr x acceleration D force x distance WHY

Q. abody of mass 1 kg begins to move under theAction ofa time dependent force F (2ti +3t2jN, and j are unit vectors along x and yWhat power will be developed by the force at the time t

Q. 8. A body of mass 10 kg moves with a velocity of 2m per sec along a circular path of radius 8m. The power produced by the body will be?

Q. A particle of mass m moves on a straight line withits velocity varying with the distance travelled. If therelation between velocity and distance is v Kx (Kis constant), then find the work done by the forcesduring a displacement x 0 to x = d.VERYmkd2(1)2mk2d2(2)2mdok34)2mk^° d23)2

Q. Instantaneous power can be equal to average power.

1. False
2. True

Q. A block of mass $m$ is located on a horizontal plane. The block acquires a horizontal velocity $v_0$ due to friction. Find the mean power developed by the friction force during the motion of the body. The frictional cofficient is $\mu =0.3,m=2\text{kg}$ and $v_0=5\text{m/s}$ (Take $g=10{\text{m/s}}^2$)

1. $30\text{watt}$
2. $45\text{watt}$
3. $60\text{watt}$
4. $15\text{watt}$

Q. A particle of mass $0.01\text{kg}$ and charge ${10}^{-6}\text{C}$ is placed at rest in a uniform electric field $2\times {10}^6\text{N/C}$ and then released. The kinetic energy attained by the particle after moving a distance of $2\text{m}$ is
[Assume gravity free space]

1. $3\text{J}$
2. $2\text{J}$
3. $1\text{J}$
4. $4\text{J}$

Q. If a force $\overrightarrow{F}=(7\hat{i}-6\hat{j}+2\hat{k})\text{N}$ and velocity $\overrightarrow{v}=(6\hat{i}+\hat{k})\text{m/s},$ then the instantaneous power is

1. $46\text{watts}$
2. $42\text{watts}$
3. $57\text{watts}$
4. $44\text{watts}$

Q. Two blocks of masses m₁ and m₂ are connected by a spring of spring constant k. The block of mass m₂ is given a sharp impulse so that it acquires a velocity v₀ towards right. Find (a) the velocity of the centre of mass, (b) the maximum elongation that the spring will suffer.
Figure

Q. Water falls from a height of $80\text{m}$ at the rate of $20\text{kg/s}$ to operate a turbine. The losses due to frictional force are $20$ % of the energy. How much power is generated by the turbine? $(g=10\frac{m}{s^2})$

1. $10.2\text{kW}$
2. $12.8\text{kW}$
3. $12.3\text{kW}$
4. $7.0\text{kW}$

Q. A particle of mass M starting from rest undergoes uniform acceleration.If the speed acquired in time T is V, the power delivered to the particle is

Q. A force applied by an engine of a train of mass $2.05\times {10}^6\text{kg}$ changes its velocity from $5\text{m/s}$ to $25\text{m/s}$ in $5\text{minutes}$. The power of the engine is

1. $1.025\text{MW}$
2. $2.05\text{MW}$
3. $5\text{MW}$
4. $6\text{MW}$

Q. A block of mass $m$ is located on a horizontal plane. The block acquires a horizontal velocity $v_0$ due to friction. Find the mean power developed by the friction force during the motion of the body. The frictional cofficient is $\mu =0.3,m=2\text{kg}$ and $v_0=5\text{m/s}$ (Take $g=10{\text{m/s}}^2$)

1. $30\text{watt}$
2. $45\text{watt}$
3. $60\text{watt}$
4. $15\text{watt}$

Q. The time taken by an engine of power $10\text{kW}$ to lift a mass of $200\text{kg}$ to a height of $40\text{m}$ is $(g=10m{s}^{-2})$

1. $2s$
2. $4s$
3. $8s$
4. $16s$

Q. A dipole is placed in an electric field as shown. In which direction will it move ?
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1. Towards the left as its potential energy will increase.
2. Towards the left as its potential energy will decrease.
3. Towards the right as its potential energy will increase.
4. Towards the right as its potential energy will decrease.

Q. The graph below shows power $\left(P\right)$ delivered by the engine of a car as a function of time.


Find out the final velocity of car, if initial velocity of the car is $10\text{m/s}$ and mass is $200\text{kg}$.

1. $5\sqrt{10}\text{m/s}$
2. $5\sqrt{5}\text{m/s}$
3. $20\text{m/s}$
4. $15\text{m/s}$

Q. 105. A box of mass 4 kilogram is pushed on a rough ( u = 0.2 ) heavy trolley with an acceleration 2 m/s relative to trolley. If the trolley moves with an acceleration of 3 m/s on the ground, the work done in pushing the box for 2s is (1) 60J (2) 120J (3) 180J (4) 280J

Q. A car of mass m is driven with acceleration a alomg a straight level road against a cons†an t extrnal resistive force R .when the velocity of the car is V , the rate at which the engine of car is doing work will be 1.RV 2.maV 3.(R +ma)V 4.(ma-R)V

Q. In one dimensional motion, a body experiences a force, which is a linear function of time t, F = 2t acting in the direction of motion( initially the body was at rest) l. The work done by the force in first 4 seconds is

Q.

if force acting on a particle is given by

F=-2i and its velocity is given by V=+3j find the power of the object