menu search
brightness_auto
Feel free to answer or ask any questions.
If you are new here please see how to use or FAQ.
more_vert

A person sitting in the ground floor of a building notices through the window, of height 1.5 m, a ball dropped from the roof of the building crosses the window in 0.1 s. What is the velocity of the ball when it is at the topmost point of the window ? (g–10 m/s2)

(1) 20 m/s

(2) 15.5 m/s

(3) 14.5 m/s

(4) 4.5 m/s

thumb_up_off_alt 2 like thumb_down_off_alt 0 dislike
more_vert
h=ut+1/2*at^2
-1.5=u(0.1)+1/2*(-10)(0.1)^2
-15/10=u(0.1)+1/2*(-10)(1/100)
-15=10[u(0.1)+1/2*(-10)(1/100)
-15=u-0.5
u=-15+0.5
u=-14.5m/s

1 Answer

more_vert
 
verified
Best answer

S= ut + 1/2 at2

-1.5=0.1u-1/2 *10*(0.1)2

u=-15.5

therefore, negative sign indicates that it is in downward motion.

Thanks guys!!

thumb_up_off_alt 2 like thumb_down_off_alt 0 dislike

Related questions

Welcome to Jee Neet QnA, where you can ask questions and receive answers from other members of the community.

1.1k questions

772 answers

366 comments

79 users

...