Question

A truck of mass 15 tons moving with $1m{s}^{-1}$ collides with a stationary truck of mass 10 tons and automatically connected to move together. the total K.E after collision

• A. 4500 J
• B. 7500 J
• C. 3000 J
• D. 0 J

Answer 1

The correct option is A 4500 J

Using momentum conservation for inelastic collision,

$m_1{u}_1+m_2{u}_2=V(m_1+m_2)$

$15\times 1+10\times 0=(15+10)V$

$\Rightarrow V=\frac{15}{25}=0.6$ms${}^{-1}$

Kinetic energy after collision,

$K.E{.}_{After}=\frac{1}{2}m{V}^2=\frac{1}{2}\times 25000\times \left(\frac{36}{100}\right)=4500$ J .