Question

Car A has twice the mass of car B , and car A has the half the kinetic energy of car B . How do their speeds compare?

Answer 1

Answer:

Speed of car A is half the speed of car B.

Explanation:

Kinetic energy, $KE=\frac{1}{2}mv^2$

Car A has twice the mass of car B.

         $m_A=2m_B$

Car A has the half the kinetic energy of car B

         $KE_A=\frac{1}{2}KE_B$

We have

          $KE_A=\frac{1}{2}KE_B\\\\\frac{1}{2}m_Av_A^2=\frac{1}{2}\times \frac{1}{2}m_Bv_B^2\\\\\frac{1}{2}\times 2m_Bv_A^2=\frac{1}{2}\times \frac{1}{2}m_Bv_B^2\\\\v_A^2=\frac{v_B^2}{4}\\\\v_A=\frac{v_B}{2}$

Speed of car A is half the speed of car B.