A particle has initial velocity $\left(3\hat{\mathrm{i}}+4\hat{\mathrm{j}}\right)$ and has acceleration $\left(0.4\hat{\mathrm{i}}+0.3\hat{\mathrm{j}}\right)$. Its speed after 10 s:

1. 7 units

2. $7\sqrt{2}$ units

3. 8.5 units

4. 10 units

A boat is sent across a river in perpendicular direction with a velocity of 8 km/hr. If the resultant velocity of boat is 10 km/hr, then velocity of the river is : 

1. 10 km/hr

2. 8 km/hr

3. 6 km/hr

4. 4 km/hr

A train is moving towards east and a car is along north, both with same speed. The observed direction of car to the passenger in the train is 

1. East-north direction

2. West-north direction

3. South-east direction

4. None of these

If the body is moving in a circle of radius r with a constant speed v, its angular velocity is:

1. v²/r

2. vr

3. v/r

4. r/v

A motorcyclist going round in a circular track at a constant speed has:

1. constant linear velocity.

2. constant acceleration.

3. constant angular velocity.

4. constant force.

A particle moves with constant angular velocity in a circle. During the motion its:

The angular speed of a flywheel making 120 revolutions/minute is: 

1. $2\pi rad/s$

2. $4{\pi }^{2}rad/s$

3. $\pi rad/s$

4. $4\pi rad/s$

The angle turned by a body undergoing circular motion depends on time as $\theta ={\theta }_0+{\theta }_{1}t+{\theta }_2{t}^2$. Then the angular acceleration of the body is 

(1) θ₁

(2) θ₂

(3) 2θ₁

(4) 2θ₂

A bomb is dropped from an aeroplane moving horizontally at constant speed. When air resistance is taken into consideration, the bomb 

(1) Falls to earth exactly below the aeroplane

(2) Fall to earth behind the aeroplane

(3) Falls to earth ahead of the aeroplane

(4) Flies with the aeroplane