Question

on a trip a family averaged 65km/hr for the first hour 50km/hr for the second hour and 58 km/hr for the third hour. what was their average speed?

Answer 1

a physics question @alfers101 please post this in physics section

Answer 2

though I will help you wait

Answer 3

given :
1) at t =1 hr. , average speed = 65 kmph
2) at t = 2hr. , average speed = 58 kmph

so we know that:
\[\large{\frac{\textbf{total distance travelled}}{\textbf{total time taken}}=\textbf{average speed}}\]

Answer 4

Oh sorry wait

Answer 5

also remember that \[\huge \frac{\text{speed}_1 + \text{speed}_2}{2} \ne \text{average speed}\]
just saying

Answer 6

ok

Answer 7

thanks

Answer 8

thanks? u got it soo soon @alfers101 ?

Answer 9

no i still dont :( but i have the idea but i dont know how to answer this

Answer 10

oh k so what is the idea?

Answer 11

do you have the answer alfers101?

Answer 12

FIrst, find how far they drove. Use speed*time= distance
they drove 65km/hr for the first hour: distance= 65*1
do the same thing for the 2nd hour (using the new speed), and the 3rd hour
add up the distances

now use speed*time= distance
speed= distance/time

distance will be the total distance
time will be the total time ( 3 hours)