In a series of physics demos students of varying mass are placed on large massless carts and deliver impules to each others carts some carts are loaded with equal mass in other cases are unequal
some push off each other

measuring things 1 litre of water

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg

pythagoras' theorem

square root (-5^2+9^2)

square root (25+81)

square root (106)

angle is tan^-1(9/5)

neg x, pos y