A man walks 7 km East in 2.5 hours, 2 km west in one hour, 3 km East in 1.5 hour and then 5 km West in 2 hours.
a) Do the diagram
b) Find the distance covered by the man?
c) Find the magnitude and direction of the displacement of the man.
d) What is the man's average speed for the whole journey?
e) What is the man's average velocity for the whole journey?
Answers
Given: A man walks 7 km in 2 hrs
Later he walks 2 km in 1 hour
We need to find the average speed and average velocity
Solution:
We know that
Speed = Total distance / Total time
Total distance travelled by man = 7 km + 2 km = 9 km
Total time taken = 2 + 1 = 3 hrs
Average speed = 9/3 = 3 km/hour.
Velocity = Total displacement / Total time
Average velocity will be the same as average speed in this case since there is no direction change mentioned.
Therefore Total Displacement = Total Distance
average velocity = average speed = 3 km/hour.
Hence
Average speed = 3 km/hr.
Average velocity = 3 km/hr.
Answer:
d)speed for the whole journey?= 3.1667 km/hr
e)man's average velocity for the whole journey? =1.5 km/hr
Explanation:
d) average speed is given by:
the total distance traveled/ total time taken
= (7+2.5)km/(2+1)hrs =9.5/3 km/hr
= 3.1667 km/hr
e) average velocity is given by:
displacement/total time
displacement is 7km-2.5km = 4.5 km (since he walked 2.5 km in the opposite of his initial direction)
Therefore average velocity = 4.5/ (2+1)
=4.5/3
=1.5 km/hr