Question

A 15 g toy car moving to the right at 24 cm/s has a head-on nearly elastic collision with a 21 g toy car moving in the opposite direction at 31 cm/s. After colliding, the 15 g car moves with a velocity of 41 cm/s to the left. Find the speed of the second car after the collision.

Answer 1

Answer:

The speed of the second toy car after collision is $v_2 = 0.155 \ m/s$

Explanation:

Let movement to the right be positive and the opposite negative

From the question we are told that

   The mass of the car is  $m_1 = 15 \ g = \frac{15}{1000} = 0.015 \ kg$

    The initial velocity of the car is  $u_1 = 24 \ cm /s = 0.24 m/s$

    The mass of the second toy car  $m_2 = 21 g = 0.021 \ kg$

    The initial velocity of the car is $u_2 = 31 \ cm/s =- 0.31 m/s$

    The final velocity of the first car is  $v = 41cm/s = - 0.41 m/s$

     From law of momentum conservation we have that

     $m_1 u_1 + m_2 u_2 = m_1 v_1 + m_2 v_2$

substituting values

       $(0.015* 0.24) +( 0.021 * -0.31) = (0.015 * -0.41 ) + 0.021 v_2$

      $-0.00291 = -0.0615 + 0.021 v_2$

      $v_2 = 0.155 \ m/s$