Their common speed is 1.53 m/s.
<h3>What is speed?</h3>
Speed can be defined as the ratio of the distance to the time of a body in motion.
To calculate their final speed, we use the formula below.
Formula:
- mu+m'u' = V(m+m')............. Equation 1
Where:
- m = mass of the Lee
- m' = mass of Mat
- u = initial speed of Lee
- u' = initial speed of Mat
- V = Their common speed.
make V the subject of the equation
- V = (mu+m'u')/(m+m')........... Equation 2
From the question,
Given:
- m = 40 kg
- m' = 80 kg
- u = 4.6 m/s
- u' = 0 m/s
Substitute these values into equation 2
- V = [(40×4.6)+(80×0)]/(40+80)
- V = 184/120
- V = 1.53 m/s.
Hence, Their common speed is 1.53 m/s.
Learn more about speed here: brainly.com/question/3004254
