Question

3. Two cars, both with a mass of 500 kg, are traveling down a road. The first car has a velocity of 65 m/s east and the second car has a velocity of 85 m/s west. (Chapter 2 – Pages 54-55) a. Calculate the momentum of both cars showing the appropriate equation from your textbook and your work with units in order to receive credit. b. Which car has the larger momentum? Explain how you know.

Answer 1

Answers:

a) Momentum for Car 1: $p_{1}=32500kg.m/s$ East

   Momentum for Car 2:$p_{2}=42500kg.m/s$ West

b) Car 2 has the greater momentum

Explanation:

a) The linear momentum $p$ is given by the following equation:

$p=m.v$ (1)

Where $m$ is the mass of the object and $v$ its velocity.

In this case both cars have a mass of $500kg$ but different velocities ($v_{1}=65m/s$ east for car 1 and $v_{2}=85m/s$ west for car 2).

For Car 1:

$p_{1}=m.v_{1}$ (2)

$p_{1}=(500kg)(65m/s)$ (3)

$p_{1}=32500kg.m/s$ (4)

For Car 2:

$p_{2}=m.v_{2}$ (5)

$p_{2}=(500kg)(85m/s)$ (6)

$p_{2}=42500kg.m/s$ (7)

b) Having the result of the lineal momentum for both cars, we know Car 2 has the larger momentum, this can be known because Car 2 has a greater velocity.

So, if momentum is directly proportional to the mass and the velocity of the object, both objects have the same mass but different velocities; the object with greater mass will have the greater momentum.