Question:
State Newton's First Law of motion.
Answer:
Newton's First Law of motion states if a body is in state of rest, it will remain in the state of rest and if it is in the state of motion it will remain in the state of the motion with same velocity and same direction unless an external force is applied on it.
Force and Laws of Motion
Q 1.
What is the total momentum of a bullet and a gun before firing?
Q 2.
A car weighs 1500 kg.Its speed time graph is shown in Fig. Calculate the force required at the end of 5 seconds to bring the car to a stop within one second.
Q 3.
Do action-reaction forces produce the same magnitude of acceleration ?
Q 4.
Using second law of motion, derive the relation between force and acceleration.
Q 5.
A hammer of mass 500 g, moving at 50 m/s, strikes a nail. The nail stops the hammer in a very short time of 0.01 s. What is the force of the nail on the hammer ?
Q 6.
Discuss briefly Galileo's ideas about motion.
Q 7.
What is the other name for Newton's first law of motion ?
Q 8.
Are action-reaction forces simultaneous ?
Q 9.
A person in a bus tends to fall backwards, when it starts suddenly ?
Q 10.
Define momentum of a body.
Q 11.
What is one newton force ?
Q 12.
What acceleration is produced by a force of 5 N acting on a body of mass 20 kg ?
Q 13.
How Newton's Second law of motion is different from First law?
Q 14.
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 15.
Fill in the blanks :
The study of motion of a body under the action of a force is called ______.
Q 16.
Which Newton's law is also known as the Law of Inertia?
Q 17.
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 18.
Can balanced forces move a body at rest ?
Q 19.
On what factor does inertia of a body depend ?
Q 20.
When a branch of a tree is shaken, some of the fruits may fall down.Why ?
Q 21.
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 22.
Fill in the blanks :
On what factor does the inertia of a body depends? ____________
Q 23.
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 24.
Can balanced forces change the shape and size of an object?
Q 25.
How is force related to acceleration produced in a body by its application?
Q 26.
What is the SI unit of impulse.
Q 27.
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 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.
An automobile vehicle has a mass of 1500 kg.What must be the force between the vehicle and road if the vehicle is to be stopped with a negative acceleration of 1.7
?
Q 30.
A bullet of mass 10 g travelling horizontally with a velocity of 150
strikes a 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 31.
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 32.
Can balanced forces change the shape and size of a body ?
Q 33.
State Newton’s first law of motion. Hence define force and inertia.
Q 34.
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 35.
Why is it advised to tie any luggage kept on the roof of a bus with a rope?
Q 36.
What are contact forces? Give examples
Q 37.
While catching a fast moving ball, fielder gradually pulls his hand backwards. Give reasons.
Q 38.
It is difficult to balance our body when we accidentally slip on a peel of banana. Explain why?
Q 39.
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?
Q 40.
What is collision? What are the types of collision?
Q 41.
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 42.
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 43.
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 44.
Two persons manage to push a motorcar of mass 1200 kg at a uniform velocity along a level road. The same motorcar can be pushed by three persons to produce an acceleration of 0.2m s-2. With what force does each person push the motorcar?
(Assume that all persons push the motorcar with the same muscular effort.)
Q 45.
Fill in the blanks :
A cyclist on a levelled road does not come to rest immediately even he stops pedalling. It is due to ______________.
Q 46.
Fill in the blanks :
When the playing card is flicked with the finger the coin placed over it falls in the tumbler. It is due to ____________.
Q 47.
Fill in the blanks :
The property of an object to resist changes in its rotational state of motion is called ________.
Q 48.
What are balanced forces?
Q 49.
What did Galileo conclude on the basis of his experiments on the motion of objects?
Q 50.
Is force a scalar or vector quantity?
