A body is projected vertically upwards with a velocity ‘u’. It crosses a point in its journey at a height ‘h’ twice, just after …..

Q. A body is projected vertically upwards with a velocity ‘u’. It crosses a point in its journey at a height ‘h’ twice, just after 1 and 7 seconds. The value of u in ms-1 is (g = 10ms-2)

(a) 50

(b) 40

(c) 30

(d) 20

Ans: (b)

A body is projected with a velocity u. It passes through a certain point above the ground in t1 The time after which…..

Q. A body is projected with a velocity u. It passes through a certain point above the ground in t1 The time after which the body passes through the same point during the return journey

(a) \displaystyle (\frac{u}{g}-t_1^2)

(b) \displaystyle 2(\frac{u}{g}-t_1)

(c) \displaystyle 3(\frac{u^2}{g}-t_1)

(d) \displaystyle 3(\frac{u^2}{g^2}-t_1)

Ans: (b)

A stone projected vertically up from the ground reaches a height y in its path at t1 seconds and after further t2 seconds reaches the ground…..

Q. A stone projected vertically up from the ground reaches a height y in its path at t1 seconds and after further t2 seconds reaches the ground. The height y is equal to

(a) \displaystyle \frac{1}{2} g(t_1 + t_2)

(b) \displaystyle \frac{1}{2} g(t_1 + t_2)^2

(c) \displaystyle \frac{1}{2} g(t_1 . t_2)

(d) \displaystyle g(t_1 . t_2)

Ans: (c)

The friction of air causes a vertical retardation equal to 10% of the acceleration due to gravity. The maximum height & time …..

Q. The friction of air causes a vertical retardation equal to 10% of the acceleration due to gravity.  The maximum height and time to reach the maximum height will be decreased by

(a) 9%, 9%

(b) 11%, 11%

(c) 9%, 10%

(d) 11%, 9%

Ans: (a)