momentum = mass × velocity
We need to convert all our units to SI units, for our equation. This means momentum must be specified on kgm/s (which it conveniently is in the question), mass should be in kg and velocity should be in m/s (which it isnt so we need to convert it).
A quick hack to convert from km/h to m/s is to divide the value by 3.6 . To convert the otherway, simply multiply by 3.6 .
So
46.0/3.6 = 12.777777 m/s (recurring)
Now we can substitute these values into our equation. I will keep the speed as 46.0/3.6 for accuracy.
momentum = mass × velocity
1.40 × 109 = mass × 46.0/3.6
therefore mass =
