11.

In a uniform circular motion, the angle between the velocity and acceleration is

• 0

• 45°

• 90°

• 75°

A crate is pushed horizontally with 100 N across a 5 m floor. If the frictional force between the crate and the floor is 40 N, then the kinetic energy gained by the crate is

• 200 J

• 240 J

• 250 J

• 300 J

The potential energy of a conservative system is given by V(x) = (x² − 3x) joule, where x is measured in metre. Then its equilibrium position is at

• 1.5 m

• 2 m

• 3 m

• 1 m

An engine pumps out water continuously through a hose with a velocity v. If m is the mass per unit length of the water jet, the rate at which the kinetic energy is imparted to water is

• $\frac{1}{2} {\mathrm{mv}}^2$

• $\frac{1}{2} {\mathrm{mv}}^3$

• $\frac{1}{2} {\mathrm{m}}^2{\mathrm{v}}^2$

• mv³

A body of mass 1.5 kg rotating about an axis with angular velocity of 0.3 rad s^-1 has the angular momentum of 1.8 kg m² s^-2. The radius of gyration of the body about an axis is

• 2 m

• 1.2 m

• 0.2 m

• 1.6 m

In a two-particle system with particle masses m₁ and m₂ , the first particle is pushed towards the centre of mass through a distance d, the distance through which second particle must be moved to keep the centre of mass at the same position is

• $\frac{{\mathrm{m}}_2\mathrm{d}}{{\mathrm{m}}_1}$

• d

• $\frac{{\mathrm{m}}_1\mathrm{d}}{{\mathrm{m}}_2}$

• $\frac{{\mathrm{m}}_1\mathrm{d}}{\left({\mathrm{m}}_1 + {\mathrm{m}}_2\right)}$

The principle involved in the performance of a spinning-chair circus acrobat is

• conservation of angular momentum

• conservation of linear momentum

• conservation of energy

• principle cf moment

Two bodies of masses 4 kg and 9 kg are separated by distance of 60 cm. A 1 kg mass is placed in between these two masses. If the net force on 1 kg is zero, then its distance from 4 kg mass is

• 26 cm

• 30 cm

• 24 cm

• 32 cm

The total energy and kinetic energy of an Earth's satellite are respectively

• positive and negative

• negative and positive

• positive and positive

• negative and negative

If the earth is one-fourth of its present distance from the sun, the duration of the year will be changed to

• half of the present year

• $\frac{1}{4}\mathrm{th}$ of the present year

• $\frac{1}{8}\mathrm{th}$ of the present year 

• $\frac{7}{8}\mathrm{th}$ of the present year