A body falls freely for 10 s. Its average velocity during this journey is (Take, g = 10 ms^-2)

• 100 ms^-1

• 10 ms^-1

• 50 ms^-1

• 5 ms^-1

From the top of a tower a stone is thrown up which reaches the ground in a time t₁. A second stone thrown down with the same speed reaches the ground in a time t₂. A third stone released from rest from the same between reaches the ground in a time t₃. Then

• $\frac{1}{{\mathrm{t}}_3} = \frac{1}{{\mathrm{t}}_2} - \frac{1}{{\mathrm{t}}_1}$

• ${\mathrm{t}}_3^2 = {\mathrm{t}}_1^2 - {\mathrm{t}}_2^2$

• ${\mathrm{t}}_3 = \frac{{\mathrm{t}}_1 + {\mathrm{t}}_2}{2}$

• ${\mathrm{t}}_3 = \sqrt{{\mathrm{t}}_1 {\mathrm{t}}_2}$

Two identical charged spheres suspended from a  common point by two massless strings of lengths l, are initially at a distance d (d < l) apart because of their mutual repulsion. The charges begin to leak from both the spheres at a constant rate. As a result, the spheres approach each other with a velocity v. Then, v varies as a function of the distance x between the sphere, as

• vx

• 

• vx^-1

• 

If the magnitude of sum of two vectors is equal to the magnitude of difference of the two vectors, the angle between these vectors is,

• 90^o

• 45^o

• 180^o

• 0^o

The velocity-time graph for two bodies A and B are shown in figure. Then, the acceleration of Aand B are in the ratio

• sin 25° to sin 50°

• tan 25° to tan 40°

• cos 25° to cos 50°

• tan 25° to tan 50°