A ball is thrown vertically upwards with a velocity of 20m/s from the top of a multistorey building. The height of the point from where the ball is thrown is 25m from the ground.

(1) How high the ball will rise?

(2) How long it will be before the ball hits the ground? (Take g=10m/s^{2}

18.)On as smooth table two blocks of masses 2.5kg and 1.5kg are placed one over the other.If the coefficient of static friction between two blocks is 0.2,the maximum horizontal force to be applied on the lower block so that the two blocks move together is (g=10m/s2)

when total work done by a particle is positive :

1.KE remains constant 2. momentum increases 3. KE increases 4. KE decreases

a particle is acted upon by a force F=(i-2j+k) N . If the particle is at P(-1,2,3) , the torque of the force about Q(2,3,1) is ?

(1) Zero

(2) E

(3) $E-\frac{Ir}{2}$

(4) $E-2Ir$

A ball is thrown vertically upwards with a velocity of 20m/s from the top of a multistorey building. The height of the point from where the ball is thrown is 25m from the ground.

(1) How high the ball will rise?

(2) How long it will be before the ball hits the ground? (Take g=10m/s

^{2}h=Fv^2 /L x F

. F is the force, v is the velocity

and L is the angular momentum. Find the

dimensions of h .

(g = 10m/${s}^{2}$). Select the correct statements.

(A) Acceleration of block A, B and C are 1 m/${s}^{2}$, 3 m/${s}^{2}$and 5 m/${s}^{2}$ respectively

(B) Contact force between B & Ground is 350 N

(C) Tension in string 30N

(D) Contact force between 'B' and 'C' is 15 N

18.)On as smooth table two blocks of masses 2.5kg and 1.5kg are placed one over the other.If the coefficient of static friction between two blocks is 0.2,the maximum horizontal force to be applied on the lower block so that the two blocks move together is (g=10m/s2)

when total work done by a particle is positive :

1.KE remains constant 2. momentum increases 3. KE increases 4. KE decreases

(b) how does it affect the maximum load it can support without exceeding the elastic limit ?

a particle is acted upon by a force F=(i-2j+k) N . If the particle is at P(-1,2,3) , the torque of the force about Q(2,3,1) is ?

1. 45 m/s

2. 50 m/s

3. 30 m/s

4.35 m/s