a body travel 30 meter north in 3 sec then 50 meter east in 4 sec then 100 meters south in 10 sec. Find average speed and average velocity
Answers
Answer:Speed of a body is the distance covered by the body in unit time.
Therefore Speed= \dfrac{Distance}{Time} which implies:
Distance = Speed \times Time
Time = \dfrac{Distance}{Speed}
1. In order to find speed, if :
Distance is in metre (m) and time in second (s); then the speed is in metre per second (m/s)
Distance is in Km (Km) and time in hour (h); then the speed is in Kilometer per hour (Km/h)
2. In order to find the distance, if:
Speed is in metre per second (m/s); time must be in second .
Speed is in Kilometer per hour (Km/h);time must be in hour
3. In order to find time, if:
Speed is in Kilometer per hour (Km/h), distance must be in Kilometer.
Speed is in metre per second(m/s), distance must be in metre.
Unit of Speed
\because Speed=\dfrac{Distance}{Time}
\therefore unit \: of \: speed=\dfrac{unit \: of \: distance}{unit \: of \: time}
Now, the various units of distance are metre, centimetre, Kilometre etc. and the various units of time are hour, minutes and seconds.
So, say we take the unit of distance to be centimetre (cm.) and the unit of time to be second (s.).
Speed = distance / time
Speed 1 = 30/3 mps = 10 mps
Speed 2 = 50/4 mps = 12.5 mps
Speed 3 = 100/10 mps = 10 mps
Average speed = (10+12.5+10)/3
= 32.5/3
= 10.8 mps approximately
Velocity = displacement/time
Using Pythagoras theorom
Velocity = (70×70+50×50)/ (4+3+10)
= (4900+2500) / 17
= 435.2 mps southeast approximately
:-)