Question

Lee has a mass of 40.0 kg and ice skates with a speed of 4.6 m/s.
She collides into Mat 80.0 kg) who is standing still on the ice. They
move off together. What is their final speed in m/s

Answer 1

Their common speed is 1.53 m/s.

What is speed?

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.

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