Sunday, May 3rd, 2009
maths physics speed question, please read on?
….. asked:
The momentum of the roller coaster car after 6 seconds is 9000 kg m/s.
The momentum of the car after 18 seconds is?
the answer is 45000 but i dont know how it was done since
momentum = mass x velocity
speed reading
May 6th, 2009 at 12:58 pm
speed reading
Does this problem give you the mass of the car?
Since you have given the answer of 45000 (increased from 9000), and we know that the mass of the car is constant, that means that there is a change in velocity over the change in time (ie, the distance).
Let’s assume 10^3 as the mass of the car.
p=mv and v=d/t
so, p=m(d/t)
tp=dm
6(9000)=d(1000)
d=54
54 m in 6s which is 9m/s.
tp=dm
18(45 x 10^3)=d(1000)
(810)(1000)=d(1000)
810=d
810 m in 18 s., so velocity is changing over time, ie, velocity is increasing.