Question

A bullet of mass 100 gm leaves a riffle with an initial velocity of 100 m/sec and strikes the earth at the same level with a velocity of 50 m/sec. The work in overcoming the resistance of air will be then

• A. 80 J
• B. 50 J
• C. 375 J
• D. 475 J

Answer 1

The correct option is C 375 J

Given,

Mass, $=100gm=0.1kg$ m

Initial and final velocity, $u=100m{s}^{-1}andv=50m{s}^{-1}$

Resistance work by air = Loss in Kinetic Energy

Loss in kinetic energy, $\frac{1}{2}m(v^2-u^2)=\frac{0.1}{2}({100}^2-{50}^2)=375J$

Hence, The work in overcoming the resistance of air will be $375J$