Two bodies of mass 10 kg and 5 kg moving in concentric orbits of radii R and r such that their periods are the same. Then the ratio between their centripetal acceleration is 

1. R/r

2. r/R

3. R²/r²

4. r²/R²

A particle is moving in a horizontal circle with constant speed. It has constant 

1. Velocity

2. Acceleration

3. Kinetic energy

4. Displacement

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. $4\pi rad/s$

An electric fan has blades of length 30 cm as measured from the axis of rotation. If the fan is rotating at 1200 r.p.m, the acceleration of a point on the tip of the blade is about

1. 1600 m/sec²

2. 4740 m/sec²

3. 2370 m/sec²

4. 5055 m/sec²

The angular speed of seconds needle in a mechanical watch is:

1. $\frac{\pi }{30}$ rad/s

2. 2π rad/s

3. π rad/s

4. $\frac{60}{\pi }$ rad/s

A particle moves with constant speed \(v\) along a circular path of radius \(r\) and completes the circle in time \(T\). The acceleration of the particle is:
1. \(2\pi v / T\)
2. \(2\pi r / T\)
3. \(2\pi r^2 / T\)
4. \(2\pi v^2 / T\)

If a_r and a_t represent radial and tangential accelerations, the motion of a particle will be uniformly circular if:
1. a_r = 0 and a_t = 0
2. a_r = 0 but a_t \(\neq\) 0
3. a_r \(\neq\) 0 but a_t = 0
4. a_r \(\neq\) 0 and a_t \(\neq\) 0$\mathrm{}$
 

          
1. \(3.14~\text{m/s}\)
2. \(2.0~\text{m/s}\)
3. \(1.0~\text{m/s}\)
4. zero

A stone tied to the end of a string of \(1\) m long is whirled in a horizontal circle with a constant speed. If the stone makes \(22\) revolutions in \(44\) s, what is the magnitude and direction of acceleration of the stone?