## A man is holding an umbrella at angle 30° with vertical with lower end towards himself, which is appropriate angle ….

Q: A man is holding an umbrella at angle 30° with vertical with lower end towards himself, which is appropriate angle to protect him from rain for his horizontal velocity 10 m/s. Then which of the following will be true-

(A) rain is falling at angle 30° with vertical, towards the man

(B) rain may be falling at angle 30° with vertical, away from the man

(C) rain is falling vertically

(D) none of these

Click to See Solution :
Ans: (B)
Sol:

Let v = velocity of rain ; Hence Possible values of α are
-30º < α < 90º

## A ball is thrown horizontally from the top of a tower. What happens to the horizontal component of its velocity ?

Q: A ball is thrown horizontally from the top of a tower. What happens to the horizontal component of its velocity ?

(a)Increases

(b) Decreases

(c) Remains unchanged

(d) First decreases and then increases

Ans: (c)
Sol: As there is No acceleration in horizontal direction hence the horizontal component of its velocity remains unchanged .

## A swimmer is moving in a square course in a river. The flow velocity of the river is 3 m/s and the velocity of swimmer relative to water is 5 m/s….

Q: A swimmer is moving in a square course in a river. The flow velocity of the river is 3 ms-1 and the velocity of swimmer relative to water is 5 ms-1. The total distance travelled by the swimmer is 80 m.  Time taken by swimmer (in second) to complete the course is 22.5 n . Find the value of n.

Ans. 9

## Two particle P and Q are moving in gravity free space with their respective velocities V_p = -i + 2j -2k  ms-1 and V_p = -4i + 2j + 3k  ms-1. At t = to , the separation between them is minimum. Find the value of 10 to .

Q: Two particle P and Q are moving in gravity free space with their respective velocities $V_P = -\hat{i} + 2\hat{j} -2\hat{i}$  ms-1 and $V_Q = -4\hat{i} + 2\hat{j} + 3\hat{k}$ ms-1. At t = to , the separation between them is minimum. Find the value of 10 to .

Ans. 5