Calculate the momentum of a 5 tonne truck at 50km/h

We know momentum= mass (kg) X Velocity (m/s)

So we need to do these conversions:  1tonne=1000kg so 5 tonnes is 5x1000kg = 5000kg 

There are 1000km in a meter so 50x1000= 50000m/h to get this into m/s we know there are 60mins in an hour and 60 sec in a min 60x60 =3600sec in an hour so 50000x3600 = 1.8E8 m/s

To find the momentum we use the first forumula giving 1.8E8 x 5000 = 9E11kgm/s