Don't listen to the other guy I just took the test and got it wrong because of him..
I re-took it and the correct answer is
A) Safety Data Sheets (SDS)
So, first the formula of Impulse is
I = force * time
We have force but no time.
Then, find time.
Next find acceleration,
F = mass * acceleration
5 = 3 * a
1.67 m/s^2
Next find time,
Acceleration = change in velocity / time
Change in velocity is velocity final - velocity initial
1.67 = 3 - 9 / time
Time = 3.6 s (round to 2 s.f.)
Lastly,
Impulse = force * time
Impulse = 5 * 3.6
Impulse is 18 Ns
The period of a wave is the time it takes the wave to complete one cycle (at a fixed location).
So if a wave completes one cycle in <em>2 seconds</em>, then that is its period.
I'm Pretty sure it's FRICTION