TIME,DISTANCE AND SPEED
Distance covered per unit time is called SPEED
i,e., speed=distance/time
the above equation can be rearranged as
time=distance/speed
distance=speed*time
1.km/hr to m/sec conversion
zkm/hr = | z x | 5/18 | m/sec |
2.m/sec to km/hr conversion
z m/sec = | z x | 18/5 | km/hr |
3.If the ratio of the speeds of A and B is a : b, then the ratio of the
the times taken by then to cover the same distance is |
1/a |
: |
1/b |
or b:a |
4.Suppose a man covers a certain distance at x km/hr and an equal distance at y km/hr. Then,
the average speed during the whole journey is |
2xy |
km/hr. |
||
x + y |
WORKSAMPLES:
1. | A person crosses a 600 m long street in 5 minutes. What is his speed in km per hour? | |||||||||||||||||||
SOLUTION WITH EXPLANATION:
= 2 m/sec. Converting m/sec to km/hr (see important formulas section)
= 7.2 km/hr |