First Law of Motion

Q. A thin rod of length L and mass M is bent at its mid-point into two halves so that the angle between them is 90^° . The moment of inertia of the bent rod about an axis passing through the bending point and perpendicular to the planedefined by the two halves of the rod is

Q. 69.Two disc of same moment of inertia rotating about their regular axis passing through centre and perpendicular to their plane of disc with angular velocity omega 1 and 2. They are brought about face to face coinciding the axis of rotation. The expression for loss of energy during this process is

Q. 10. A thin wire of length and mass m is bent in the form of a semicircle. The moment of inertia about an axis perpendicular to its plane and passing through the end of the wire is ml2 (3) 2ml2 (4) ml2 (1) 2 (2) 2m

Q. A: When a man is walking on a rough road, the work done by frictional force is zero. R: Frictional force acts in the direction of the motion of the man in this case. (1) Assertion and reason are true and reason is the correct explanation of assertion (2) Assertion and reason are true but reason is not the correct explanation of the assertion (3) Assrertion is true but reason is false (4) Assertion is fals

Q. A trolley of mass 300 kg carrying a sandbag of 25 kg is moving uniformly with a speed of 27 km/h on a frictionless track. After a while, sand starts leaking out of a hole on the floor of the trolley at the rate of 0.05 kg s¯¹. What is the speed of the trolley after the entire sand bag is empty ?

Q.

The inability of body to change its state of uniform motion or rest is known as

1. Newton's law of gravitation

2. Newton's second law of motion

3. Law of inertia

4. Newton's third law of motion

Q. Masses kept at the corners of a regular pentagon as shown. Dis†an ce between centroid and any vertex of Pentagon is R. If another point mass m0 is kept at the centroid of the Pentagon then force acting on it due to Masses is?

Q. Figure shows a flywheel of radius 10 cm. Its moment of inertia about the rotation Axis is 0.4 kg m2. A massless string passes over the flywheel and a mass 2 kg is attached at its lower end. Angular acceleration of the flywheel in rad/s2 is nearly

Q.

On a stationary sail boat, air is blown from a fan attached to the boat. The boat will

1. not move

2. spin around

3. more in the direction in which air is blown.

4. move in the opposite direction to the direction in which air is blow.

Q. from a height two balls are thrown with same speed upward and downward .they take t1 and t2 time to reach the ground if third ball is dropped from same height find time taken by it to reach the ground

Q.

Can a force change the shape of an object? Give one example.

Q. three equal masses 2m each are placed at the vertices an equilateral triangle pqR , what is the force on mass m of the mass at the vertex P is quadruple

Q. 17. A particle at rest, falls under gravity (g 9.8 m/s2)such that it travels 53.9 m in last second of itsjourney. Total time of fall is(1) 4s(2) 5 s(3) 6s(4) 7 s

Q. Two bodies have their moments of inertia I and 2I respectively about their axis of rotation.If their kinetic energies of rotation are equal their angular momenta will be in the rat

Q.

When a force is applied to a body its shape changes.

1. True

2. False

Q. Find the moment of inertia through com of a solid hemisphere. The axis is at angle 37 degrees with the horizontal.

Q.

Passengers in a bus lean forward as bus suddenly stops. This is due to

1. Impulse

2. Change in momentum

3. Change in speed

4. Inertia

Q.

why newton first law of motion called the law of inertia

Q.

A bar magnet is tied to a string and hung from the ceiling. Gravitational force of attraction by the earth is pulling the magnet down. According to Newton's first law, the magnet should move towards ground as it is acted upon by a force. Then why isn't it happening.

1. Repulsion by Earth's Magnetic field holds it in air

2. Air friction is balancing the magnet

3. The tensile strength of the string is balancing the gravitational pull by earth.

4. The volume of air displaced gives a Buoyant force to hold it up

Q. how mosquito travel with velocity of train when it is inside the train any flying continuously .also law of inertia is not applied for it

Q. 10. A force vector f=vector v × vector A is exerted on a particles in addition to the force of gravity, where vector v is the velocity of the particlesand vector A is a constant vector in the horizontal direction. With what minimum speed a particle of mass m be projected so that it continues to move undeflected with a constant

Q. 5. A heavy rod of mass M and length l is lying upon smooth horizontal floor. A small and light particle ofmass m (<< M) moving horizontally with velocity u strikes with the rod and sticks with it. During thesubsequent motion, the force exerted upon one halfof rod due to the other half, will be

Q. a rocket is fired upwards such that its engine takes 10 sec to explode fully. its v t graph is shown in the figure Acceleration due to gravity is 10 then the total time for which the rocket moves upward i

Q.

Paint gun depends upon:

1. Archimedes' principle

2. Newton law of motion

3. Bernoulli's principle

4. Boyle's law

Q. 17. Preeti reached the metro station and found the the escalator was not working . she walked up the stationary escalator in time t1 .on other day if she remains stationary on the moving escalator then time t2.time taken by her to walk up on moving escalator will be

Q. what is the difference between absolute and relative motion?

Q. A block of mass M is pulled along a smooth horizontal surface with a rope of mass m by applying a force F. The acceleration of the block will be?

Q.

The escape velocity (v ) of a body depends upon the mass (m) of body, gravitational
acceleration (g) and radius(R) of the planet .Derive the relation for escape velocity
dimensionally.

Q. Why is motion always relative in nature

Q. A particle falling from rest under gravity covers height H in 2.828 second. The time taken by it to cover first half of the height is approximately