Question

A train moving with velocity 72 km/h and momentum 8×10^5 kg m/s. Find the mass of train.

Answer 1

Explanation:

$72km \div hr = 72 \times 5 \div 18 \\ = 20m \div s$

$p = m \times v \\ 8 \times 10 {}^{5 } = m \times 20m \div s \\ m = 8 \times 10 {}^{5} \div 20 \\ m = 4 \times 10 {}^{4}$

in this question conversation factor 5/18

and. p=mv . these two formulas are important