Question:
Name any two applications of the law of conservation of linear momentum.
Answer:
(i) Flight of jet planes and rockets
(ii) Recoiling of a gun on firing.
Force and Laws of Motion
Q 1.
A bullet of mass 10 g travelling horizontally with a velocity of 150 m/s strikes a stationary wooden block and comes to rest in 0.03 s. Calculate the distance of penetration of the bullet into the block. Also calculate the magnitude of the force exerted by the wooden block on the bullet.
Q 2.
A force of 5 N gives a mass
an acceleration of 10
,and a mass
,an acceleration of 20
.What acceleration would it give if both the masses were tied together ?
Q 3.
A stone of 1 kg is thrown with a velocity if 20
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 ?
Q 4.
A man pushes a box of mass 50 kg with a force of 80 N.What will be the acceleration of the box ? What would be the acceleration if the mass were halved ?
Q 5.
A body of mass 1 kg is kept at rest.A constant force of 6-0 N starts acting on it.Find the time taken by the body to move through a distance of 12 m.
Q 6.
A bullet of mass 50 g is fired from a gun of mass 6 kg with a velocity of 400 m/s.Calculate the recoil velocity of the gun.
Q 7.
Do action-reaction forces act on the same body ?
Q 8.
Define momentum of a body.
Q 9.
Derive the relation F = ma,where the symbols have their usual meanings.
Q 10.
What would be the force required to produce an acceleration of 2
in a body of mass 12 kg ? What would be the acceleration if the force were doubled ?
Q 11.
A hockey ball of mass 200 g travelling at 10 m/s is struck by a hockey stick so as to return it along its original path with a velocity of 5 m/s.Calculate the change in momentum of the hockey ball by the force applied by the hockey stick.
Q 12.
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 13.
What is the SI unit of force ?
Q 15.
Honey and Sunny are two friends.Both are financially well off.Honey is fond of driving an SUV while Sunny enjoys driving Tata Nano.Honey explains to Sunny the risks of driving a light vehicle and Sunny explains to Honey the cost factor.
Read the above passage and answer the following questions :
(i) With whom do you agree,with Honey or with Sunny?
(ii) Explain, why?
(iii) Which values of life do you learn from this discussion?
Q 16.
State Newton's First Law of motion.
Q 17.
Fill in the blanks :
When a car enters a curved path, the person sitting in it is thrown outwards. This is because of the property of ______________.
Q 18.
Fill in the blanks :
It is dangerous to jump out of a moving bus because due to _________ one falls forward.
Q 19.
Force can change the shape and size of an object. Give an example.
Q 20.
Why does a bicycle slow down when the cyclist stop pedalling?
Q 21.
Define 1 Newton force.
Q 22.
Which would require a greater force : accelerating a 2 kg mass at 5
or a 4 kg mass at 2
?
Q 23.
What are balanced forces ?
Q 24.
What is the SI unit of momentum ?
Q 25.
What is the total momentum of the bullet and the gun on firing ?
Q 26.
Name any two applications of the law of conservation of linear momentum.
Q 27.
Show that kg-
and N-s represent the same quantity.Which is that quantity ?
Q 28.
What is force ? What is inertia ? How is inertia measured ?
Q 30.
What are balanced and unbalanced forces?
Q 31.
Are there any limitations to Newton's Laws of motion?
Q 32.
Fill in the blanks :
An umbrella protects us from rain it is based on the property of _____________.
Q 33.
Which Newton's law is also known as the Law of Inertia?
Q 34.
What do you mean by a resultant force?
Q 35.
Which principle is involved in the working of a jet plane?
Q 36.
How is force related to momentum of a body?
Q 37.
A 150 g ball travelling at 30 m/s strikes the palm of a player’s hand and is stopped in 0 06 sec. Calculate the force exerted by the ball on the hand.
Q 38.
A force of 4 N acts on a body of mass 2 kg for 4 s.Assuming the body to be initially at rest,find (a) its velocity when the force stops acting (b) the distance covered in 10 s after the force starts acting.
Q 39.
Two objects of masses 100 g and 200 g are moving along the same line in the same direction with velocities of 2 m/s and 1 m/s,respectively.They collide and after the collision, the first object moves at a velocity of 1.67 m/s in the same direction.Determine the velocity of the second object
Q 40.
Is force a scalar or a vector ?
Q 41.
Can balanced forces move a body at rest ?
Q 42.
Is momentum a scalar or vector ?
Q 43.
In the above question,which body undergoes greater change in momentum ?
Q 44.
Name the various effects of force.
Q 45.
What is one newton force ?
Q 46.
Why does a gun recoil on firing ? Obtain an expression for recoil velocity of gun.
Q 47.
In the following example, try to identify the number of times the velocity of the ball changes:
A football player kicks a football to another player of his team who kicks the football towards the goal. The goalkeeper of the opposite team collects the football and kicks it towards a player of his own team?
Also identify the agent supplying the force in each case.
Q 48.
A force of 5 N changes the velocity of a body from 10
to 20
in 5 sec.How much force is required to bring about the same change in 2 sec ?
Q 49.
Name the categories of forces based on interaction.
Q 50.
What are non-contact forces? Give examples.
