A cat walks in a straight line, which we shall call the x-axis, with the positive direction to the right. As an observant physicist, you make measurements of this cat's motion and construct a graph of the feline's velocity as a function of time (Fig. E2.30). (a) Find the cat's velocity at t = 4.0 s and at t = 7.0 s.

Video transcript

Hey everyone. So today we're dealing with the problem about velocity versus time graphs. Now we are told that there is a physics student who is analyzing the motion of a dog as it making a chase. And the dog is moving in a straight line in the positive X direction and the positive X direction. The student measures the dogs motion and contracts the velocity versus time graph. And we are being asked to determine the dog's velocity at times 2.5 seconds and time to six seconds. So let's write that out. We're asked to find what is V, What is velocity at 2.5 seconds And what is V at six seconds? No, we actually don't have to do anything else other than look at her craft. Right? So at time is equal to two seconds because time is the X axis here at times 2.5 seconds. And that's right here. It intersects with the point on the line right here, lining up with hoops lining up with negative 1.5. So velocity at 2.5 seconds is equal to negative 1.5 m/s. No, if we look at the velocity at six seconds, well we have to do the exact same thing. Let me do this in rent at six seconds. It intersects with the graph at the point of two seconds. Oops, that's a horrible line. Two seconds. So velocity At time six seconds is two m/s. And those are our answers. So looking at our answer choices, this lines up directly with answer choice, B, Velocity at 2.5 seconds is negative 1.5 m/s, and velocity of six seconds is two m/s. I hope this helps, and I look forward to seeing you all in the next one.