Laws Of Motion Question 281
Question: An object of mass 10 kg moves at a constant speed of$ 10m{{s}^{-1}} $ . A constant force that acts for 4 sec on the object gives it a speed of $ 2m{{s}^{-1}} $ in opposite direction. The force acting on the object is
Options:
A) -3N
B) -30 N
C) 3N
D) 30 N
Show Answer
Answer:
Correct Answer: B
Solution:
[b] $ Hereu=10m{{s}^{-1}},v=-2m{{s}^{-1}},t=4s,a=? $
Using $ a=\frac{v-u}{t}=\frac{-2-10}{4}=-3m/s^{2} $
$ \therefore \text{Force, }F\text{=}ma=10\times ( -3 )=-30N $
