Recent questions tagged class 9

When the objects are not moving the forces are

asked Oct 29, 2017 by priyanka.c

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Which of the following equations relate velocity, acceleration and time?

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The velocity of an object at rest is

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The figure below shows the velocity -time graph of an object. The total distance travelled by it is

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It is easier to roll a heavy stone up a sloping road than to lift it because

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The area under uniform acceleration-time graph for a given interval of time gives

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A motion in which the distance of the moving particle from a fixed point is always constant during motion is called

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The numerical ratio of average speed to average velocity is

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A train 100 m long is moving with a velocity of 60 km/hr. The time it takes to cross 1 km bridge is

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Acceleration motion is always due to

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Read the following passage and answer the question below An object remains in the state of rest or uniform motion in a straight line unless compelled to change that state by an applied force. In other words all objects resist a change in their state of motion. In a qualitative way, the tendency of undisturbed objects to stay at rest or to keep moving with the same velocity is called inertia. That is why the first law of motion is also called law of inertia. Certain experiences that we come across while travelling in a motorcar can be explained on the bases of this law of inertia. We tend to remain with respect to the seat until the driver applies a braking force to stop the motorcar. With the application of brakes, the car slows down but our body continues in the same state of motion because of inertia. QUESTION : When we stand in a stationary bus and the bus starts suddenly, we are thrown backwards, this is because of

asked Oct 29, 2017 by priyanka.c

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Read the passage below and answer the question An object remains in the state of rest or uniform motion in a straight line unless compelled to change that state by an applied force. In other words all objects resist a change in their state of motion. In a qualitative way, the tendency of undisturbed objects to stay at rest or to keep moving with the same velocity is called inertia. That is why the first law of motion is also called law of inertia. Certain experiences that we come across while travelling in a motorcar can be explained on the bases of this law of inertia. We tend to remain with respect to the seat until the driver applies a braking force to stop the motorcar. With the application of brakes, the car slows down but our body continues in the same state of motion because of inertia. QUESTION : Newton's first law defines only

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A body of mass 5 kg and another body of mass 10 kg have same kinetic energy. Which of the two will have greater momentum?

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When two protons are brought towards each other, will the potential energy increase or decrease ?

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What will happen to the potential energy when a spring is compressed

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The average work done by a human heart while it beats once is 0.5 J. Calculate the power used by the heart if it beats 72 times in a minute.

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What will be work done by a car of mass 400 kg moving through a distance of 2m along a straight horizontal road against gravity?

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Moon has no atmosphere because

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Weight of an object will be zero when

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Distance between a compression and a rarefraction is

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Visible light is an example of

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The distance between two consecutive crests is

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Sound waves travel faster on a rainy day than on a dry day because

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Mechanical waves transfer

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Air friction ________ the velocity of the satellite.

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Moon travelers tie heavy weight at their back before landing on the moon because

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Read the passage below and answer the following question Take an empty plastic bottle. Close the mouth of the bottle with an airtight stopper. Put it in a bucket filled with water. We can see that the bottle floats. Push the bottle into the water. We can feel an upward push. If we try to push it further down, it will be difficult to push it deeper and deeper. Now release the bottle. It bounces back to the surface.The force due to the gravitational attraction of the earth acts on the bottle in the downward direction. So the bottle is pulled downwards. But the water exerts an upward force on the bottle. Thus the bottle is pushed upwards. Also the weight of an object is the force due to gravitational attraction of the earth. When the bottle is immersed, the upward force exerted by the bottle by the water on the bottle is greater than its weight. Therefore it rises up when released. To keep the bottle completely immersed the upward force on the bottle due to water should be balanced. This can be achieved by an externally applied force acting downwards. This force must be at least equal to the difference between the upward force and the weight of the bottle. QUESTION : If the upward force exerted by the liquid is equal to the downward force due to the weight of the object then the object will

asked Oct 29, 2017 by priyanka.c

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Read the passage below and answer the following question Take an empty plastic bottle. Close the mouth of the bottle with an airtight stopper. Put it in a bucket filled with water. We can see that the bottle floats. Push the bottle into the water. We can feel an upward push. If we try to push it further down, it will be difficult to push it deeper and deeper. Now release the bottle. It bounces back to the surface.The force due to the gravitational attraction of the earth acts on the bottle in the downward direction. So the bottle is pulled downwards. But the water exerts an upward force on the bottle. Thus the bottle is pushed upwards. Also the weight of an object is the force due to gravitational attraction of the earth. When the bottle is immersed, the upward force exerted by the bottle by the water on the bottle is greater than its weight. Therefore it rises up when released. To keep the bottle completely immersed the upward force on the bottle due to water should be balanced. This can be achieved by an externally applied force acting downwards. This force must be at least equal to the difference between the upward force and the weight of the bottle. QUESTION : Which of the statement is not true? 1. An object floats if its density is lesser than that of the liquid in which it is immersed 2. The density of a substance is mass per unit area 3. The weight of an object is due to the gravitational pull on it 4. The downward force exerted by the liquid is called buoyancy

asked Oct 29, 2017 by priyanka.c

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A truck and a car are moving with the same kinetic energy are stopped by applying brakes. Which will stop at a smaller distance?

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What will happen to the kinetic energy of the particle, if its momentum is doubled?

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Sand is spread on tracks covered with snow. Why?

asked Oct 29, 2017 by priyanka.c

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A balloon has a mass of 10g in air. The air escapes from it at an uniform rate with a velocity of 5cm/s and the balloon shrinks completely in 2.5 s. What is the average force acting on the balloon.

asked Oct 29, 2017 by priyanka.c

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A thief jumps from the roof of a house with a box of weight W on his head. What will be the weight of the box as experienced by the thief during the jump?

asked Oct 29, 2017 by priyanka.c

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The following figure shows the time-acceleration graph for a particle in rectilinear motion. What will be the average acceleration in first twenty seconds?

asked Oct 29, 2017 by priyanka.c

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A particle moves along a circle of radius R. It starts from a point and moves in an anticlockwise direction. What will be the displacement made by it along the diameter?

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When will the average velocity be equal to the instantaneous velocity?

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The difference between pulse and wave is

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The ceilings of concert halls are generally curved because

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A person clapped his hands near a cliff and heard the echo after 3s. If the speed of sound is 330m/s, find the distance of the cliff from the person.

asked Oct 29, 2017 by priyanka.c

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The types of waves produced by a slinky is

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Read the following passage and answer the question given below The word energy is often used in our daily life, but in science we give it a precise meaning. Let us consider the following examples : when a fast moving cricket ball hits a stationary wicket, the wicket is thrown away. Similarly, an object when raised to a height gets the capability to do work. You must have seen that when a raised hammer falls on a nail placed on a piece of wood, it drives the nail into the wood. We have also observed children winding a toy and when the toy is placed on the floor it starts moving. When a balloon is filled with air and when we press it we notice a change in shape. As long as we press it gently, it can come back to its original shape when the force is withdrawn. However if we press the balloon hard it might explode. In all these cases the object acquire through different means the capability of doing work.An object having the capability to do work is said to posses energy. The object which does work losses energy and the object on which work is done gains energy. QUESTION : The energy possessed by the toy when it moves on the floor is

asked Oct 29, 2017 by priyanka.c

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Read the following passage and answer the question given below The word energy is often used in our daily life, but in science we give it a precise meaning. Let us consider the following examples : when a fast moving cricket ball hits a stationary wicket, the wicket is thrown away. Similarly, an object when raised to a height gets the capability to do work. You must have seen that when a raised hammer falls on a nail placed on a piece of wood, it drives the nail into the wood. We have also observed children winding a toy and when the toy is placed on the floor it starts moving. When a balloon is filled with air and when we press it we notice a change in shape. As long as we press it gently, it can come back to its original shape when the force is withdrawn. However if we press the balloon hard it might exploded. In all these cases the object acquire through different means the capability of doing work. An object having the capability to do work is said to possess energy. The object which does work loses energy and the object on which work is done gains energy. QUESTION : Work done on an object is

asked Oct 29, 2017 by priyanka.c

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A stone thrown up vertically returns to the thrower after 5s, then the maximum height reached by it is

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What happens to the gravitational force if the distance between objects is tripled?

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Two balls have masses m and (1/2)m and velocity v and (1/2) v respectively. The ratio of their momentum is

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When a tree is shaken, its leaves and fruits fall down, this is because of

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The agent which causes the change in speed of a freely falling object is

asked Oct 29, 2017 by priyanka.c

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Which of the following statements are not correct? 1. If the speed-time graph is a straight line parallel to time axis, then it indicates that the object is moving with uniform speed 2. The area below the velocity-time graph gives the distance covered by the object. 3. Acceleration is taken as positive if it is in the direction opposite to the direction of velocity. 4. The velocity-time graph for non-uniformly accelerated motion is always a straight line.

asked Oct 29, 2017 by priyanka.c

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If the weight of a body is 20gwt as measured by a spring balance, then its mass is

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Pascal is unit for

asked Oct 28, 2017 by priyanka.c

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