Joseph jogs from one end A to the other end B of a straight 30 m road in 20 seconds and then turns around and jogs 100m back to point C in another 10sec. what are joseph's average speeds and velocities in jogging from A to C.
Answers
Explanation:
Let us first understand what is meant by average speed and average velocity.
Average speed of a body is defined as the total distance covered by the body divided by the total time taken by the body to cover this distance.
Average velocity of a body is defined as the net displacement of the body divided by the total time taken by the body.
(a) It is given that Joseph jogs on a straight road of 300m in a time interval of 2 minutes and 30 seconds, which is equal to 150seconds150seconds. Therefore, when Joseph jogs from point A to point B, he covers a distance of 300m in time of 150seconds150seconds.Hence, his average speed is 300m150s=2ms−1300m150s=2ms−1.Since it is a straight road and he jogs in a single direction in this case, his displacement is equal to 300m.
Hence, his average velocity is 300m150s=2ms−1300m150s=2ms−1.
(b) Then it is given that he turns back and points B and jogs on the same road but in the opposite direction for a time interval for 1 minute and covers a distance of 100m.If we consider the whole motion of Joseph, i.e. from point A to point C, then he covers a total distance of 300m+100m=400m300m+100m=400m. And he covers this total distance in a time interval of 2.5min+1min=3.5min=210s2.5min+1min=3.5min=210s.
Therefore, his average speed for this journey is 400m210s=1.9ms−1400m210s=1.9ms−1.
For the same journey is displacement is equal to the distance between the points A and C,i.e. 300m−100m=200m300m−100m=200m.
Hence, his average velocity for this case is 200m210s=0.95ms−1200m210s=0.95ms−1.
Note: The distance covered by a body is the total length of the route by which the body travels. It is just a magnitude.Displacement of a body is a vector joining the initial position and the final position of the body. Its magnitude is equal to the length of the line segment joining the initial and final positions.
Answer:
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