If ${a_r}$ and ${a_t}$represent radial and tangential accelerations, the motion of a particle will be uniformly circular if
${a_r} = 0$ and ${a_t} = 0$
${a_r} = 0$ but ${a_t} \ne 0$
${a_r} \ne 0$ but ${a_t} = 0$
${a_r} \ne 0$ and ${a_t} \ne 0$
An electron is moving in a circle of radius $2 \,m$ with speed $4 \,m / s$ Find the acceleration of the electron. (in $m / s ^{2}$)
car moves on a circular road. It describes equal angles about the centre in equal intervals of time. Which of the following statement about the velocity of the car is true
Can you associate vectors with $(a)$ the length of a wire bent into a loop, $(b)$ a plane area, $(c)$ a sphere ? Explain.
A particle of mass $m$ describes a circle of radius $r$. The centripetal acceleration of the particle is $4/r^2$. What will be the momentum of the particle?
A clock has $75 \mathrm{~cm}, 60 \mathrm{~cm}$ long second hand and minute hand respectively. In $30$ minutes duration the tip of second hand will travel $x$ distance more than the tip of minute hand. The value of $x$ in meter is nearly (Take $\pi=3.14$ ) :