Answer:
GIVEN
u is 40m/s and v=60m/s
time is 4s
therefore acceleration =60-40/4
=20/4=5m/s^2
b)next 2 sec=70m/s
Density of powder 1 = 0.5 g / 45 cm^3 = 1/90 g/cm^3
Density of powder 2 = 1.3 g / 65 cm^3 = 1/50 g/cm^3
Therefore the densities of the two powders are different, hence chemical reaction has occurred.
(note: none of the other choices make sense. In fact, a different density does not necessarily indicate a chemical change, see paragraph below).
Density of powders are not definitive unless they are each of the same size and texture. For example, granular sugar, rock sugar, and icing sugar all have different densities. I would conclude that this experiment does not lend to a reliable answer.
Therefore, the ball has a velocity of 4m/s.
Honestly would say A not sure
Yes it would be the same your weight would change:)
