The one which does not represent a force in any context is

• Friction

• Impulse

• Tension 

• Weight

The work-energy theorem states that the change in

• kinetic energy of a particle is equal to the work done on it by the net force

• kinetic energy of a particle is equal to the work done by one of the forces acting on it.

• potential energy of a particle is equal to the work done on it by the net force

• potential energy of a particle is equal to the work done by one of the forces acting on it

A car of masses 1500 kg is lifted up a distance of 30 m by crane A in 0.5 minutes. The second crane B does the same job in 1 minute. The ratio of their powers is

• 1 : 2

• 2 : 1

• 1 : 1

• 1 : 4

Water from a hose pipe of radius 5 cm strikes a wall normally at a speed of 5 ms^-1. The force exerted on the wall in newton is

• $13.5 \mathrm{\pi }$

• $6.25 \mathrm{\pi }$

• $62.5\mathrm{\pi }$

• $27\mathrm{\pi }$

The position vectors of two identical particles with respect to the origin in three-dimensional coordinate system are r₁ and r₂. The position vector of centre of mass of the system is given by

• r₁ + r₂

• 2(r₁ + r₂)

• r₁ − r₂

• $\frac{{\mathrm{r}}_1 + {\mathrm{r}}_2}{2}$

If a body of moment of inertia 2 kg m² revolves about its own axis making 2 rotations per second, then its angular momentum (in Js) is

• $2 \mathrm{\pi }$

• $4 \mathrm{\pi }$

• $6 \mathrm{\pi }$

• $8 \mathrm{\pi }$

A rigid body is the one in which

• it can have only rotational motion

• it can have only translational motion

• the distances between all pairs of particles of the body do not change

• its centre of mass always lies inside the material of the body

A body hanging from a massless spring stretches it by 3 cm on Earth's surface. At a place 800 km above the Earth's surface, the same body will stretch the spring by (Radius of Earth = 6400 km)

• $\left(\frac{34}{27}\right) \mathrm{cm}$

• $\left(\frac{64}{27}\right) \mathrm{cm}$

• $\left(\frac{27}{64}\right) \mathrm{cm}$

• $\left(\frac{27}{34}\right) \mathrm{cm}$

The acceleration due to gravity on the surface of a planet is one-fourth of the value on Earth. When a brass ball is brought to this planet, its

• mass is halved

• weight is halved

• mass becomes one-fourth

• weight becomes one-fourth

Polar satellites

• are high altitude satellite

• are widely used for telecommunication

• are used for environmental studies

• go around the Earth in a East-West direction