Class 11th

If length of stretched string is increased by 50% keeping mass per unit length same, then in order to keep its frequency of vibration constant, its tension must be increases by

A car is skidding on an icy road with speed  $v$ and tyres are rotating with angular speed $\frac{v}{3R}$ , where $R$  is the radius of tyres. The distance travelled by car in one rotation of tyres is

Two balls each of mass 1kg moving in opposite directions with speed 15m/s  collides and rebounds with the same speed. The magnitude of impulse imparted to each ball due to other is

The velocity of boat m still water is 10 ms $m{s}^{-1}$ ${}^{}$ . The river flow velocity is 5 ms $m{s}^{-1}.$ ${}^{}$

If ${}_{}$ $v_b$ ,= $$ velocity of boat with respect to river velocity, $v_b=$ ${}_{}$ actual velocity of boat (i.e. with respect to bank), $v_r=$ ${}_{}$ velocity of stream, then the value of $v_b$ ${}_{}$ is

The correct graph between logeR and loge( - 0) during cooling of a body may be (R is the rate of cooling and 0 is surrounding temperature)

The radius of circle, the period of revolution $T$ , initial position and sense of revolution are indicated in the figure. x-projection of the radius vector of rotating particle $P$  is

If force (F), mass (M), length (L) are taken as fundamental quantities, dimensions of time will be

The velocity of a particle is given by $\text{exception 25:}$ $v=\sqrt[]{180-16x}m/s$ . Its acceleration will be

If $$ $a\cdot b=\left|a*b\right|$ , then the $\theta$ angle $$ between a and b will be

Consider the following two statements .

(A)The gravitational force on a particle inside a spherical shell is zero.

(B) Total mechanical energy of a body on earth's surface may be positive.

Which of the following options is correct?