Laws Of Motion Question 259
Question: A body of mass 5 kg starts from the origin with an initial velocity $ \overrightarrow{u}=30\hat{i}+40\hat{j}m{{s}^{-1}} $ . If a constant force $ \overrightarrow{F}=-(\hat{i}+5\hat{j})N $ acts on the body, the time in which the y?component of the velocity becomes zero is [EAMCET (Med.) 2000]
Options:
A) 5 seconds
B) 20 seconds
C) 40 seconds
D) 80 seconds
Show Answer
Answer:
Correct Answer: C
Solution:
$ u _{y}=40m/s $ , $ F _{y}=-5N $ , $ m=5kg $ .
So $ a _{y}=\frac{F _{y}}{m}=-1m/s^{2} $
(As $ v=u+at $ ) \ $ v _{y}=40-1\times t=0 $
therefore $ t=40\sec $ .
