Physics Practice: Work, Power and Energy (Mock Test 4 - Expert)
1. Expert Analysis: A pump on the ground floor of a building can pump up water to fill a tank of volume $30 \text{ m}^3$ in $15 \text{ min}$. If the tank is $40 \text{ m}$ above the ground, and the efficiency of the pump is $30\%$, the electric power consumed is: (Density of water $= 1000 \text{ kg/m}^3$)
2. Clinical Logic: In a nuclear power plant, a mass defect of $1 \text{ \mu g}$ occurs per second. What is the power output of the reactor?
3. Data-Based: A body moves under the action of a constant power $P$. The displacement $S$ after time $t$ is proportional to:
4. Experimental Setup: In a collision between two steel balls on a friction-less surface, which of the following is NOT conserved?
5. A force $F = -kx$ acts on a particle. The graph between Potential Energy ($U$) and displacement ($x$) will be a:
6. A machine gun fires $60$ bullets per minute, each with a velocity of $700 \text{ m/s}$. If mass of each bullet is $50 \text{ g}$, the power developed by the gun is:
7. A block of mass $M$ is pulled by a force $F$ at an angle $\theta$ to the horizontal. If the block moves with constant velocity $v$, the power delivered is:
8. The mass-energy equivalence $E = mc^2$ implies that:
9. Data Logic: A car of mass $1000 \text{ kg}$ accelerates from rest to $20 \text{ m/s}$ in $10 \text{ s}$. The average power delivered by the engine (ignoring friction) is:
10. In a perfect elastic collision between two identical masses, one initially at rest:
11. A wind turbine converts wind energy into electrical energy. If the wind speed doubles, the power output (ideally) becomes:
12. A spring of force constant $k$ is cut into two equal halves. The force constant of each half is:
13. Expert Setup: A bullet loses $1/20$ of its velocity in passing through a plank. The minimum number of similar planks required to stop the bullet is:
14. When a ball is dropped from a height $h$ on a floor, it rebounds to height $h'$. The coefficient of restitution $e$ is:
15. A body of mass $m$ is projected with velocity $v$ at an angle of $60^{\circ}$ with the horizontal. Its kinetic energy at the highest point is:
16. The work done by a gas during expansion against a constant external pressure $P$ is:
17. A force of $10 \text{ N}$ acts on a body for $2 \text{ s}$ and changes its velocity from $5 \text{ m/s}$ to $10 \text{ m/s}$. The work done is:
18. Potential Energy of a system increases if work is done:
19. If the work done in stretching a spring by $2 \text{ cm}$ is $0.5 \text{ J}$, the work done in stretching it by $4 \text{ cm}$ is:
20. The gravitational potential energy of a body of mass $m$ at the surface of the Earth (radius $R$, mass $M$) is: