|
Define kinetic energy and potential energy. Write an expression for KE of a body of mass m moving with speed v. Find the kinetic energy of stone of 10 kg moving with a velocity of 10 ms^-1
|
|
0
|
4108
|
July 1, 2016
|
|
Define work, energy and power. Give the SI units for each of these quantities. A man whose mass is 80 kg climbs up 30 steps of the stairs in 30 s. If each step is 12.5 cm in height, calculate the power used in climbing the stairs, (g = 10 m s^-2)
|
|
0
|
2286
|
July 1, 2016
|
|
(a) Define kinetic energy. (b) The masses of scooter and bike are in the ratio of 2 :3 but moving with same speed of 108 km h^-1. Compute the ratio of their kinetic energy
|
|
0
|
3045
|
July 1, 2016
|
|
Define power. Write commercial unit and SI unit of electrical energy. An electrical geyser of 1.5 kW works for 2 hours. Find the electrical energy units consumed in a day
|
|
0
|
8250
|
July 1, 2016
|
|
Define: (a) power (b) work done (c) kinetic energy. Give SI unit of each
|
|
0
|
2230
|
July 1, 2016
|
|
(a) What is the commercial unit of energy ? Give its relationship with SI unit of energy. (b) An electric bulb of 60 W is lighted for 10 hours everyday. How many units of electrical energy is consumed by this bulb in one day?
|
|
0
|
2202
|
July 1, 2016
|
|
(a) An arrow moves forward when released from a stretched bow. Explain the transformation of energy in the process. (b) A boy of mass 50 kg climbs up a vertical height of 100 m. Calculate the amount of potential energy he gains
|
|
0
|
6958
|
July 1, 2016
|
|
Explain that the flying bird has; potential and kinetic energy and give their expressions
|
|
0
|
2900
|
July 1, 2016
|
|
Define 1 watt of power. A lamp consumes 1000 J of electrical energy in 10 s. Calculate its power
|
|
0
|
5052
|
July 1, 2016
|
|
(a) Is it possible that a body be in accelerated motion under the action of a force, yet no work is being done by the force? Explain with an example. (b) Two bodies of masses m1 and m2 have equal kinetic energies.What is the ratio of their linear momenta?
|
|
0
|
4181
|
July 1, 2016
|
|
Four persons jointly lift a 250 kg box to a height of lm and hold it. (a) Calculate the work done by the persons in lifting the box. (b) How much work do they do just holding it ? (c) Why do they get tired while holding it ? (g = 10 m s^2)
|
|
0
|
4975
|
July 1, 2016
|
|
A boy throws a rubber ball vertically upwards. What type of work is done; (a) by the force applied by the boy (b) by the gravitational force ? Support your answer with reason
|
|
0
|
1201
|
July 1, 2016
|
|
(a) The potential energy of a freely falling object decreases progressively. Does this violate the law of conservation of energy ? Why ? (b) An object is dropped from a height h. When is its (i) potential energy maximum? (ii) kinetic energy maximum?
|
|
0
|
4181
|
July 1, 2016
|
|
(a) Define one watt. (b) A lamp consumes 1000 J electrical energy in 10 s. What is its power?
|
|
0
|
869
|
July 1, 2016
|
|
Define power. A boy of mass 45 kg climbs up 20 steps in 20 sec. If each step is 25 cm high, calculate the power of the boy used in climbing. (Take g = 10 m s^-2)
|
|
0
|
3701
|
July 1, 2016
|
|
(a) Define potential energy. Write an expression for potential energy of an object of mass m raised through a height h.(b) Find the energy possessed by an object of mass 10 kg when it is raised to a height of six metre above the ground.Given g- 9.8 m s^-2
|
|
0
|
7835
|
July 1, 2016
|
|
(i) Define power. Mention its SI unit. (ii) A boy of mass 50 kg runs up a staircase of 40 steps in 8 s. If the height of each step is 15 cm, find his power. (Given, g = 10 m s^-2)
|
|
0
|
830
|
July 1, 2016
|
|
(i) Define the term potential energy. Write the SI unit of potential energy. (ii) A body of mass 50 kg is situated at a height of 10 m. What is its potential energy? (Given g = 10 m s^-2)
|
|
0
|
3210
|
July 1, 2016
|
|
(a) Can a body have energy without having momentum ? Explain. (b) Can a body have momentum without having energy? Explain
|
|
0
|
2251
|
July 1, 2016
|
|
(i) State the laws of floatation. (ii) Define buoyancy. State the factors on which buoyant force depends ? (iii) A boy gets into a floating boat. (a) What will happen to the weight of water displaced ? (b) What will happen to the buoyant force?
|
|
0
|
1387
|
July 1, 2016
|
|
(a) Define relative density. Give its mathematical farm. (b) The mass of an iron cube having an edge length 1.5 cm is 50 g. Find its density. (c) The volume of a 250 g sealed tin is 400 cubic cm. Find the density of the tin in g cm^-3. S
|
|
1
|
975
|
July 1, 2016
|
|
What is meant by buoyancy? Why does an object float or sink when placed on the surface of a liquid?
|
|
0
|
2527
|
July 1, 2016
|
|
(a) Why are railway tracks laid on large sized concrete sleepers ? (b) While drawing water from a well, the bucket of water appears to be heavier as it comes out of the water
|
|
0
|
2683
|
July 1, 2016
|
|
(i) When an object is immersed in a fluid, name the two forces acting on it. (ii) On which factor the magnitude of the upward force acting on this object depends ? (iii) When will this object sink?
|
|
0
|
6571
|
July 1, 2016
|
|
State Archimedes’principle. The following figures show three identical blocks of wood floating in three different liquids A, B and C of densities d1, d2, and d3 respectively. Which of these has the highest density ? Give reason to justify your answer
|
|
1
|
2329
|
July 1, 2016
|
|
Define buoyant force.An object of volume 5 cm3 is immersed first in water and then in salt solution. In which case will it experience a greater buoyant force ? What will be the effect on the buoyant force, if the volume of the object is increased to 8 cm3
|
|
0
|
1046
|
July 1, 2016
|
|
The density of turpentine at 293 K is given as 870 kg m^-3. Identify and write the names of substances that sink in turpentine at the same temperature
|
|
1
|
3480
|
July 1, 2016
|
|
Ram places a piece of iron on the surface of water. What will happen ? Give reason
|
|
0
|
1253
|
July 1, 2016
|
|
(a) Distinguish between density and relative density of a substance. (b) The relative density of silver is 10.8. If the density of water is 103 kg m^-3, find the density of silver
|
|
0
|
11971
|
July 1, 2016
|
|
State Archimedes' Principle. A ball weighing 4 kg of density 4000 kg m^-3 is completely immersed in water of density 1000 kg m^-3. Find the apparent weight of the ball in water. (g = 10m s^-2)
|
|
0
|
1562
|
July 1, 2016
|