Work Energy And Power Question 251
Question: A straight bar, of mass 15 kg and length 2 m, at rest on a frictionless horizontal surface, receives an instantaneous impulse of 7.5 Ns perpendicular to the bar. If the impulse is applied at the mid-point of the bar, the energy transferred is
Options:
A) 3.2 J
B) 1.9J
C) 3.8 J
D) 2.5 J
Show Answer
Answer:
Correct Answer: B
Solution:
[b] $ J=m( v _{f}-v _{i} )or7.5=15( v _{f}-0 ) $
$ \Rightarrow v _{f}=0.5m/s $
$ \therefore ~~K=\frac{1}{2}mv^{2}=\frac{1}{2}\times 15\times {{0.5}^{2}}=1.9J $
