JEE Main & Advanced
Physics
Motion in a Straight Line / सरल रेखा में गति
Question Bank
Motion Under Gravity
question_answer
A man drops a ball downside from the roof of a tower of height 400 meters. At the same time another ball is thrown upside with a velocity 50 meter/sec. from the surface of the tower, then they will meet at which height from the surface of the tower [CPMT 2003]
A) 100 meters
B) 320 meters
C) 80 meters
D) 240 meters
Correct Answer:
C
Solution :
Let both balls meet at point P after time t.
The distance travelled by ball A, \[{{h}_{1}}=\frac{1}{2}g{{t}^{2}}\] The distance travelled by ball B, \[{{h}_{2}}=ut-\frac{1}{2}g{{t}^{2}}\] \[{{h}_{1}}+{{h}_{2}}=400\ m\] Þ\[ut=400,\ t=400/50=8\ sec\] \[\therefore \] \[{{h}_{1}}=320\ m\ \ \text{and}\ \ {{h}_{2}}=80\ m\]