Basic suvat stuff
a, b and c are 3 points lying in that order on a straight line with ab =60 metres and ac = 80 metres. a body moves from a to b at an average speed of 10 metres per second then from b to c in a time of 4 seconds and then returns to b. the average speed for the whole journey is 5 metres per second.
find:
1. the average speed of the body during the second stage of motion from b to c.
2. the average speed of the body in moving from a to c
3. the time taken for the 3rd stage of motion from c back to b
4. the average velocity for the complete motion

1. 5 m/s

2. 8 m/s

3. 10 s

4. 3 m/s

Explanation:

1. Average speed = distance / time

s = 20 m / 4 s

s = 5 m/s

2. First, find the time to travel from A to B:

60 m = 10 m/s × t

t = 6 s

Now find the average speed from A to C:

s = 80 m / (6 s + 4 s)

s = 8 m/s

3. If t is the time traveling from C back to B, and the average speed of the whole trip is 5 m/s, then:

5 m/s = 100 m / (6 s + 4 s + t)

t = 10 s

4. Average velocity = displacement / time

v = 60 m / 20 s

v = 3 m/s

answer is c

explanation:

b. false

explanation:

suppose a rock in free fall is dropped off a cliff. after falling for 5 seconds, its speed would not be 100 m/s.