Question

A racing car accelerates uniformly through three gears, changes with the following average speed:

20 for 2.0 s
40 for 2.0 s
60 for 6.0 s

What is the overall average speed of the car?

12
13.3
40
48
37

Answer 1

average speed = total distance / total time taken..

can you calculate the total distance travelled?

Answer 2

so its 12

Answer 3

but in answer key it is 48

Answer 4

yea.. well.. you didn't answer my question yet :P

Answer 5

how?plz help me to do phy numericals

Answer 6

calculate the total distance travelled..

see in the first two seconds.. its travelling at 20m/s. right?? can u tell me the distance travelled in these 2 seconsd?

Answer 7

average speed = total distance / total time taken
20+40+60/2+2+6=12

Answer 8

20, 40 AND 60 ARE the speeds.. not the distances!

Answer 9

so how we calculate distances

Answer 10

u tell me.. concentrate on the first part..

in first 2 seconds.. it travels with 20m/s.. so what do you think is the distance travelled??

Answer 11

40 for first 2 sec?

Answer 12

perfect..

now next 2 seconds.. it moves with a speed of 40m/s.. so whats the distance in these two seconds?

Answer 13

480 total dis?

Answer 14

yess

Answer 15

so now you understand?!

Answer 16

so now i get it how it 48

Answer 17

yup.. always make a habit of writing units.. ok.. so you ll never miss out on writing units in your answer paper ever!

Answer 18

thank u
i need more help 4 phy 4 few days .whats time u came online?

Answer 19

i come online.. when i can :P..

Answer 20

ok then see u 2maro for my diagnostic test

Answer 21

:) :) :) .. see you