Question

Does anyone know these acceleration, speed & distance questions?

Answer 1

NO!! SORRY I DIDN'T GET UR QUESTION!!

Answer 2

Answer:

See explanation.

Step-by-step explanation:

See attachments

I)

For curved velocity - time graphs, you need to draw a tangent for the acceleration questions. Since it asked for acceleration at t = 10s, we need to draw a straight line that touches the graph at only one point, and that point is 10 seconds (from the question).

Now, you need to be as accurate as possible when drawing tangents, because they must touch the line at only one point.

Next, from the tangent, calculate the gradient. You can do this by drawing two more lines from the tangent to form a triangle, then divide the rise by then run or: ΔY/ΔX. And that triangle before the Y and before the X just means delta, which means change. So change in y over the change in X.  So 10/10 = 1. So 1m/s^2.

The average speed is the distance divided by the time. How do we get the distance? Get the area under the graph. Since it's a curved graph, it's more difficult to get nice shapes to calculate the area of. This is why the question asks you to estimate, no-one will sit there and count each tiny little square for the area. So we split the area under the graph into some shapes that we can calculate the area of. The more shapes you split the area into, the more accurate your answer will be.

So: Acceleration = 1m/s^2. Avg. Speed = 45m/s (2 sig fig).

II)

Be careful with this one. Just because it says last fifteen seconds, doesn't mean you take A as going from fifteen like in the attachment with the X on it.

If you draw a line up from 10 on the x-axis, you will see that it's a 17 on the y-axis.

If you draw a line up from 25 on the x-axis, you will see that it's a 13 on the y-axis.

Distance = area under graph.

Shape under graph = trapezium.

A and B are the parallel sides, and h is the vertical height, which - in this case - goes from 10 to 25. That's 15.

Formula for the area of a trapezium: 1/2(a+b)h

a = 17. b = 13.

0.5x(17+13)x15 = 225.

Distance = 225 metres.

Good luck student!