Advertisements
Advertisements
प्रश्न
Give scientific reasons.
It is easier to stop a tennis ball as compared to a cricket ball when both are travelling with the same velocity.
Advertisements
उत्तर
- The momentum of a body is the product of its mass and velocity, i.e., p = mv and the rate of change of momentum of a body is equal to the force applied, i.e., `"F" = ("m"("v" -"u"))/"t"`.
- In the given information, both the balls move with the same velocity and finally stop; thus, the force applied to stop the ball will be directly proportional to the mass of the ball.
F ∝ m - It is easier to stop a tennis ball than a cricket ball moving with the same speed because the momentum of a cricket ball will be higher than that of the tennis ball, as the mass of the cricket ball is more than tennis ball. Therefore, less force is required to stop the tennis ball when compared to the cricket ball.
APPEARS IN
संबंधित प्रश्न
A stone of 1 kg is thrown with a velocity of 20 m s−1 across the frozen surface of a lake and comes to rest after travelling a distance of 50 m. What is the force of friction between the stone and the ice?
Using a horizontal force of 200 N, we intend to move a wooden cabinet across a floor at a constant velocity. What is the friction force that will be exerted on the cabinet?
According to the third law of motion, when we push on an object, the object pushes back on us with an equal and opposite force. If the object is a massive truck parked along the roadside, it will probably not move. A student justifies this by answering that the two opposite and equal forces cancel each other. Comment on this logic and explain why the truck does not move.
Is the following statement true or false :
A rocket can propel itself in a vacuum.
What is the force which produces an acceleration of 1 m /s2 in a body of mass 1 kg ?
A girl weighing 25 kg stands on the tloor. She exerts a downward force of 250 N on the floor. What force does the floor exert on her ?
Fill in the following blanks with suitable words :
Forces in a Newton’s third law pair have equal _____________ but act in opposite _____________.
Why does a gunman get a jerk on firing a bullet ?
If action is always equal to reaction, explain why a cart pulled by a horse can be moved.
Explain how a rocket works.
If a man jumps out from a boat, the boat moves backwards. Why ?
Why is it difficult to walk on a slippery road ?
Explain why, a runner presses the ground with his feet before he starts his run.
Name the law involved in the following situation :
when person A standing on roller skates pushes another person B (also standing on roller skates) and makes him move to the right side, then the person A himself gets moved to the left side by an equal distance.
Give a scientific reason.
Even though the magnitudes of action force and reaction forces are equal and their directions are opposite, their effects do not get cancelled.
Consider a frame that is made up of two thin massless rods AB and AC as shown in the figure. A vertical force `vec"P"` of magnitude 100 N is applied at point A of the frame.
Suppose the force is `vec"P"` resolved parallel to the arms AB and AC of the frame.
The magnitude of the resolved component along the arm AC is xN.
The value of x, to the nearest integer, is ______.
[Given: sin(35°) = 0.573, cos(35°) = 0.819, sin(110°) = 0.939, cos(110°) = –0.342]
A book is resting on a table. Which of the following is the correct reaction force to the gravitational pull of the Earth on the book?
