The limiting value of static friction is slightly more than the kinetic friction. Thus more force is required to overcome the static friction than to overcome kinetic friction. Once the object starts to slide, then the surface applies only kinetic friction on the block which makes the motion a little easier.In the horse-cart case, the ground applies the static friction on the cart at rest. So, the horse has to apply more force to start the motion and after the motion starts, then less force is applied on the cart. If however, the surface is smooth, friction in negligible and the first few steps also practically require the same effort as when in motion.Hence, the assertion is correct but the reason is incorrect.

Both statements are true but the reason is not the correct explanation of the assertion.When the ball is full of water, the center of gravity of pendulum is at the center of the bob.When water starts flowing out, the center of gravity of ball shifts down, increasing the length of the pendulum, thus increasing the time period.When ball is more than half empty, the center of gravity again rises up, decreasing length of pendulum, thus decreasing the time period.

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Laws Of Motion

Q: Two spheres of same size one of mass 2 kg and another of mass 4 kg are dropped simultaneously from the top of Qutab Minar (height = 72 m ). When they are 1 m above the ground, the two spheres have the same:

Momentum , Kinetic energy and Potential energy has the term of mass in them and since they have different mass but same velocity all these quantity would be different but since acceleration is always 'g' it will be same for both.

Physics
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Two spheres of same size one of mass $2 k g$ and another of mass $4 k g$ are dropped simultaneously from the top of Qutab Minar (height $= 72 m$ ). When they are $1 m$ above the ground, the two spheres have the same:

momentum

kinetic energy

potential energy

acceleration

Medium

AIIMS

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Assertion

A horse has to pull a cart harder during the first few steps of his motion.

Reason

The first few steps are always difficult.

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

Assertion is correct but Reason is incorrect

Both Assertion and Reason are incorrect

Medium

AIIMS

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Assertion

The bob of a simple pendulum is a ball full of water. If a fine hole is made in the bottom of the ball, the time period first increases and then decreases.

Reason

As water flows out of the bob the weight of bob decreases.

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

Assertion is correct but Reason is incorrect

Both Assertion and Reason are incorrect

Hard

AIIMS

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Laws Of Motion

Physics 989 Views

Two spheres of same size one of mass 2kg and another of mass 4kg are dropped simultaneously from the top of Qutab Minar (height =72m). When they are 1m above the ground, the two spheres have the same:

A horse has to pull a cart harder during the first few steps of his motion.

The first few steps are always difficult.

The bob of a simple pendulum is a ball full of water. If a fine hole is made in the bottom of the ball, the time period first increases and then decreases.

As water flows out of the bob the weight of bob decreases.

Physics
989 Views

Two spheres of same size one of mass $2 k g$ and another of mass $4 k g$ are dropped simultaneously from the top of Qutab Minar (height $= 72 m$ ). When they are $1 m$ above the ground, the two spheres have the same: