Question:
Force can change the shape and size of an object. Give an example.
Answer:
By hammering, a block of metal can be turned into a thin sheet. By hammering, a stone can be broken into pieces.
Force and Laws of Motion
Q 1.
Are action-reaction forces simultaneous ?
Q 2.
Do action-reaction forces produce the same magnitude of acceleration ?
Q 3.
What is the unit of force in c.g.s system?
Q 4.
On what factor does inertia of a body depend ?
Q 5.
Explain why a player lowers his hands while catching a cricket ball.
Q 6.
Can every force produce motion in every object?
Q 7.
What is the SI unit of impulse.
Q 8.
The masses of two objects are 2 kg and 20 kg. Which has greater inertia ?
Q 9.
It is difficult to balance our body when we accidentally slip on a peel of banana. Explain why?
Q 10.
While driving on a highway, an insect strikes on the car windshield and splatters. Which experiences greater impact (force): an insect or the windshield?
Q 11.
Can balanced forces change the shape and size of an object?
Q 12.
A man pushes a box of mass 50 kg with a force of 80 N. What will be the acceleration of the box due to this force? What would be the acceleration if the mass were doubled ?
Q 13.
An object of mass 1 kg travelling in a straight line with a velocity of 10 m/s collides with, and sticks to, a stationary wooden block of mass 5 kg. Then they both move off together in the
same straight line. Calculate the total momentum just before the impact and just after the impact. Also, calculate the velocity of the combined object.
Q 14.
Fill in the blanks :
The study of motion of a body under the action of a force is called ______.
Q 15.
A certain force exerted for 1 -2 s raises the speed of an object from 1.8 m/s to 4.2 m/s. Later,the same force is applied for 2 second. How much does the speed change in 2 s ?
Q 16.
When a branch of a tree is shaken, some of the fruits may fall down.Why ?
Q 17.
Fill in the blanks :
When a bus starts suddenly, the bus passengers standing in the bus tend to fall backwards. It is due to _______________.
Q 18.
An object experiences a net zero external unbalanced force.Is it possible for the object to be travelling with a non-zero velocity ? If yes,state the conditions that must be placed on the magnitude and direction of the velocity.If no,provide a reason.
Q 19.
A body of mass 25 kg has momentum of 125 kg m/s. What is the velocity of the body?
Q 20.
Fill in the blanks :
It is dangerous to jump out of a moving bus because due to _________ one falls forward.
Q 21.
Define 1 Newton force.
Q 22.
Derive the unit of force using the second law of motion. A force of 5 N produces an acceleration of
on a mass
and an acceleration of 24
on a mass
.What acceleration would the same force provide if both the masses are tied together ?
Q 23.
Discuss briefly Galileo's ideas about motion.
Q 24.
Define 1N (Newton).
Q 25.
An object of mass 5 kg is moving with a velocity 4 m/s. A constant force of 20 N acts on the object. What will be the velocity after 3 s.
Q 26.
Which law of motion gives the measure of force?
Q 27.
Name the physical quantity that corresponds to the rate of change of momentum.
Q 28.
Two hockey players of opposite teams,while trying to.hit a hockey ball on the ground collide and immediately become entangled.One has a mass of 60 kg,and was moving with a velocity 5.0 m/s,while the other has a mass of 55 kg and was moving faster with a velocity of 6.0 m/s towards the first player,In which direction and with what velocity will they move after they become entangled ? Assume that the frictional force acting between the feet of the two players and ground is negligible.
Q 29.
Name the unbalanced force that stops a ball rolling on the ground.
Q 30.
What is the other name for Newton's first law of motion ?
Q 31.
In the above question, which body is damaged more ?
Q 32.
A ball is thrown vertically upwards. What is its momentum at the highest point ?
Q 33.
Derive the relation F = ma,where the symbols have their usual meanings.
Q 34.
Why does a gun recoil on firing ? Obtain an expression for recoil velocity of gun.
Q 35.
What are contact forces? Give examples
Q 36.
What are non-contact forces? Give examples.
Q 37.
State Newton's third law of motion.
Q 38.
Suppose a ball of mass m is thrown vertically upward with an initial speed v, its speed decreases continuously till it becomes zero. Thereafter, the ball begins to fall downward and attains the speed v again before striking the ground. It implies that the magnitude of initial and final momentums of the ball are same. Yet, it is not an example of conservation of momentum. Explain why ?
Q 39.
From a rifle of mass 4 kg, a bullet of mass 50 g is fired with an initial velocity of 35 m/s. Calculate the initial recoil velocity of the rifle.
Q 40.
A hockey ball of mass 200 g travelling at 10 m s-1 is struck by a hockey stick so as to return it along its original path with a velocity at 5 m s-1. Calculate the change of momentum occurred in the motion of the hockey ball by the force applied by the hockey stick.
Q 41.
Two objects having their masses in ratio 3:5 are acted upon by two forces each on one object. The forces are in the ration of 5:3. Find the ratio in their accelerations.
Q 42.
Fill in the blanks :
Newton's second law of motion states that the rate of change of ______ of a body is directly proportional to the force and takes place in the same direction as the ______.
Q 43.
Fill in the blanks :
Which has more inertia of Cricket ball or a rubber ball of the same size? __________
Q 44.
Fill in the blanks :
On what factor does the inertia of a body depends? ____________
Q 45.
Fill in the blanks :
An athlete often jumps before taking a long jump. It is due to ________________.
Q 46.
Fill in the blanks :
________ is the tendency of an object to resist a change in motion.
Q 47.
Which Newton's law is also known as the Law of Inertia?
Q 48.
Do action and reaction act on the same body?
Q 49.
What is the net momentum of gun and bullet system before firing?
Q 50.
Why mass is sometimes called coefficient of linear inertia?
