Question

What is the momentum in Kg m/s of a 10 kg truck travelling at A) 5 m/s B) 20 cm/s C) 36 km/h?​

Answer 1

Answer:

A)   50 kg m/s

B)  2 kg m/s

C)  100 kg m/s

Explanation:

Recall that momentum is a physical quantity defined by the product of the object's mass times its velocity. Therefore, in our case the truck's momentum (p) is:

A)  p = m * v = 10 kg * 5 m/s = 50 kg m/s

B) p = m * v = 10 kg * 0.20 m/s = 2 kg m/s (notice that the velocity in cm/s was converted into m/s before multiplying)

C) the conversion from km/h to m/s is a little more involved, so we taclke it first:

since 1 km = 1000 m  and 1 hour = 3600 seconds, we convert 36 km/h by replacing each unit by its m and s expression as shown below:

$36 \frac{km}{h} =36\,\frac{1000\,m}{3600\,\,s}=10\,\frac{m}{s}$

Then, the momentum is:  p = m * v = 10 kg * 10 m/s = 100 kg m/s