Laws of motion practice · Mixed difficulty

If a force of 200 N acts on a body, the momentum acquired is $150\,\,{\text{kg}}\,\,{\text{m}}{{\text{s}}^{ - 1}}.$ The period for which the force acts on the body (in sec) is

A block is projected on a rough horizontal surface with $\mu_s=0.5$ and $\mu_k=0.4$. Its initial velocity is $8 \mathrm{~m} / \mathrm{s}$. The total distance travelled by it till $t=3 \mathrm{~sec}$ is:

A gun when firing bullet recoils, this can be explained by

A body of mass $0.4 \mathrm{~kg}$ starting at origin at $t=0$ with a speed of $10 \mathrm{~m} / \mathrm{s}$ in the positive $x$-axis direction is subjected to a constant force $F=8 N$ towards negative $x$-axis. Calculate the position of the particle after 25 seconds

In a TV picture tube electrons are ejected from the cathode with negligible speed and reach a velocity of $5 \times 10^6 \mathrm{~m} / \mathrm{s}$ in travelling one centimeter. Assuming straight line motion, find the constant force exerted on the electron. The mass of the electron is $9.1 \times 10^{-31} \mathrm{~kg}$.

Assertion: If there is an isolated system of particle exists, then its total momentum is conserved.
Reason: The law of conservation of momentum follows from the second and third law of motion.

A block is given certain upward velocity along the incline of elevation $\alpha$. The time of ascent to upper point was found to be half the time of descent to initial point. The co-efficient of friction between block and incline is:

Bullets of $0.03 \mathrm{~kg}$ mass each hit a plate at the rate of 200 bullets per second, with a velocity of $50 \mathrm{~m} / \mathrm{s}$ and reflect back with a velocity of $30 \mathrm{~ms}^{-1}$. The average force acting on the plate in Newton is

An object at rest in space suddenly explodes into three parts of same mass. The momentum of the two parts are $2p\hat i\,and\,p\hat j$. The momentum of the third part

A block is placed at distance of 2 m from the rear on the floor of a truck $\left( {g = 10\,m{s^{ - 2}}} \right).$ When the truck moves with an acceleration of $8\,m{s^{ - 2}},$ the block takes 2 sec to fall off from the rear of the truck. The coefficient of sliding friction between truck and the block is

A truck starts from rest and has acceleration of $4 \mathrm{~m} \mathrm{~s}^{-2}$. A box is inside truck which is at $6 \mathrm{~m}$ from open end of truck. The coefficient of friction between box and truck is $0.1.$ How much time box will take to slip out of truck?

If the maximum possible exhaust velocity of a rocket be $2 \mathrm{~kms}^{-1}$, calculate the ratio $m_0 / m$ for it if it is to acquire the escape velocity of $11.2 \mathrm{~kms}^{-1}$ after starting from rest.

The minimum velocity $\left( {\mathrm{in\;m}{\mathrm{s}^{ - 1}}} \right)$ with which a car driver must traverse a flat curve of radius of 150 m and coefficient of friction 0.6 to avoid skidding is

A body is acted upon by balanced forces,

Observer ${O_1}$ is in a lift going upwards and ${O_2}$ is on the ground. Both apply Newton’s law, and measure normal reaction on the body

Aeroplanes are streamlined to reduce

Assertion: When a person walks on a rough surface, the frictional force exerted by the surface on the person is opposite to the direction of the tendency of motion of his legs.
Reason: If a body moves with constant velocity, it implies that it is moving along a straight line and there is no acceleration.

A force produces an acceleration of 1 m/s in a body of mass 1 kg. This form is defined as?

A body of mass $m$ moves along $X$-axis such that its position co-ordinate at any instant $t$ is $x=at^4-bt^3+ct$, where $a, b$ and $c$ are constants. What is the force acting on the particle at any instant $t$?

A car of mass 800 kg moves on a circular track of radius 40 m. If the coefficient of friction is 0.5, then maximum velocity with which the car can move is

A woman of $50 \mathrm{~kg}$ mass is standing in an elevator.
Suddenly, the cable of the elevator breaks and the elevator begins to fall freely. The force exerted by the floor of the elevator on the woman is

A block is placed on a rough horizontal floor and a horizontal force $F$ is applied on it. The force of friction $f$ by the floor on the block is measured for different values of $F$ and a graph is plotted between them. Then the graph will be a

A cannon after firing recoils due to

A truck tows a trailer of mass $1200 \mathrm{~kg}$ at a speed of $10 \mathrm{~ms}^{-1}$ on a level road. The tension in the coupling is $1000 \mathrm{~N}$. What is the power expended on the trailer?

The mass of a body measured by a physical balance in the lift at rest is found to be m. If the lift is going up with an acceleration a, its mass will be measured as

Newton's second and third laws of motion lead to the conservation of

An aircraft executes a horizontal loop at a speed of $720 \mathrm{~kmh}^{-1}$ with its wings banked at $15^{\circ}$. What is the radius of the loop?

A truck is moving on a frictionless surface with uniform velocity of $10\;\mathrm{m}{\mathrm{s}^{ - 1}}$. A leak occurs in the water tank of the truck at the rate of $2\;\mathrm{kg}{\mathrm{s}^{ - 1}}.$ What is the speed of truck after 50 s if the mass of truck is 100 kg and mass of water in truck initially was 100 kg?

Assertion: When an object is released out of an accelerated train, there is no horizontal force or acceleration on the stone.
Reason: Force acting on a body at a given time is calculated by the situation at the location of the body at that time.

A machine gun fires a bullet of 10 g with a speed of $100\,m{s^{ - 1}}.$ A person holding the gun can exert a maximum force of 100 N on it. The number of bullets that can be fired from the gun per second is