Question

wave and graph questions

Answer 1

i just have a bit of confusion

Answer 2

@matt101

Answer 3

in q 9 ans is D
is it because because there is no friction? meaning its movement is basically due to inertia?

Answer 4

Yes - no friction and perfectly elastic collisions, so kinetic energy and therefore speed is maintained the entire time. All that changes is the direction of the speed, which is why D is correct.

It's not very realistic because the speed is changing instantaneously with no acceleration.

Answer 5

okaaay got it

Answer 6

in q 7 at node the speed is maximum that means displacement is maximum am i getting it right?

Answer 7

and at anode speed is 0 so acceleration is 0

Answer 8

If you look at the graph from t=0 to t=5, you see that velocity increases to 2 m/s then decreases back to 0 m/s, all in the positive direction. This means for these first 5 seconds, all displacement is in the positive direction. Displacement is therefore maximum at 5 seconds.

From t=5 to t=10, the same thing occurs, but in the negative direction. Because the velocity change is the same over this time frame, your negative displacement brings you back to where you started. This means at t=10, you have minimal displacement because you're at you're starting point.

Acceleration is changing all throughout this graph. Acceleration is change in velocity over time, so you can say the instantaneous acceleration is the slope at a specific point on the graph. You can see that at t=0, the slope is positive and large (i.e. a large acceleration), but as you approach the peak the slope decreases (i.e. acceleration is still positive, but is getting lower).

When you hit the peak, acceleration is 0 (the slope is a horizontal line). After that, you have a small negative slope (i.e. you are starting to decelerate) - however, your velocity is still positive, so you're still moving forward. The slope remains negative and gets bigger until velocity hits 0 at t=5. However, the deceleration is still being applied and so velocity overshoots 0 and starts becoming negative! And then everything I said above repeats, just in the negative direction from t=5 to t=10.

Hope I clarified things for you somewhere in there!

Answer 9

omg u even cleared what i didn't ask but did have doubt
thank uuu!!! @matt101

Answer 10

No problem! Just keep in mind that just because velocity is 0, doesn't mean acceleration is 0 as well. Just look at the slope!

Answer 11

okaaay @matt101 :D