Question

At the local destruction derby a 400 kg Toyota moving at 10 m/s collides with an 800 kg Chevy. Both are at rest after the collision. What was the velocity of the Chevy before the collision?​

Answer 1

Answer:

$u_2 = -5m/s$

Explanation:

Given

Before Collision

Toyota

$mass = m_1 = 400kg$

$iniital\ velocity = u_1 =10m/s$

Chevy

$mass = m_2=800kg$

$initial\ velocity = u_2 = ??$

After Collision

Both Toyota and Chevy

$final\ velocity = v = 0m/s$

Required

Determine the initial velocity of Chevy

This question will be answered using the following law of conservation of momentum which states that:

$m_1u_1 + m_2u_2 = (m_1 + m_2)v$

Substitute values for m1, m2, u1 and v

$400 * 10 + 800 * u_2 = (400 + 800) * 0$

$4000 + 800u_2 = (1200) * 0$

$4000 + 800u_2 = 0$

Collect Like Terms

$800u_2 = 0 - 4000$

$800u_2 = -4000$

Divide through by 800

$\frac{800u_2 = -4000}{800}$

$u_2 = \frac{-4000}{800}$

$u_2 = -5m/s$

The velocity of Chevy before collision was 5m/s in the opposite direction of Toyota