Question

Couple questions on force vectors. Please answer slowly and give me enough time to understand & work it out:
49) A hockey puck is hit on a frozen lake and starts moving w/ a speed of 12.0 m/s. Exactly 5.0 s later, its speed is 6.0 m/s. What is the puck's average acceleration? What is the coefficient of kinetic friction b/t the puck and the ice?

50) The parachute on a race car that weights 8820 N opens at the end of a quarter-mile run when the car is traveling 35 m/s. What net retarding force must be supplied by the parachute to stop the car in a distance of 1100 m?

Answer 1

lets start with 49
how do u calculate average acceleration?

Answer 2

No clue. D;

Answer 3

ahh :P.. then u need to study more.. before trying to attempt this question!!..

Answer 4

PWNED

Answer 5

I do know all the force vector equations you know @Mashy

Answer 6

mashy just schooled you something fierce!

Answer 7

^_^

Answer 8

... I don't want to hear that. I want answers -_-;;

Answer 9

how do you find the average of *anything?

Answer 10

\[avg=\frac{a+b}{2}\]

Answer 11

If that's it then sure, I've already got the answer. But I wasn't sure, which is why I posted up the question.

Answer 12

@Mashy ^

Answer 13

Curt? xD
Yayy, I was right~!! <3

Answer 14

\[ a_{avg} = \frac{\Delta v}{\Delta t} \]
nice ^^

Answer 15

How is it v/t? o_o;;

Answer 16

"to get the average acceleration you add the two velocities and divide by the time."? ?
what nonsense? :O :O!!

Answer 17

average acceleration = Change in velocity / time taken for the change

if a car starts from rest and goes to 10 m/s .. and it takes it 10 seconds to do that.. then average acceleration = change in velocity (10 - 0) / time taken (10) = 1m/s^2

if the car already going at 30m/s brakes and comes to halt in 5 seconds.. then

average acceleration = change in velocity (0-30) / time taken (5) = -6m/s^2

Answer 18

If I'm right then fine, let's move on to the next question = n =;;
Enough with making me feel stupid LOL #nooffense

Answer 19

so whats 49th answer?

Answer 20

I'm working on 41) and 42) atm...

Answer 21

lol.. then why did u go ahead of urself. putting up 49 and all? :P

Answer 22

I just realized that an answer previously given to me by @AllTehMaffs is similar to 41).

Answer 23

I made a dumb mistake again, didn't I :/ I should stick to equations and not words. Sorry :'C

Answer 24

No, you explained it just fine!

Answer 25

But I can't give both of you medals T_T /cries

Answer 26

@Mashy thanks for catching my horrible "add the two velocities" bit - I'm bad at things sometimes :P Throw the medal at Mashy because he was correct

Answer 27

no problem :D.. she already did..see i have medal :D

Answer 28

LOL well I did say "But I can't give both of you medals".

Answer 29

Still, give the other guy a medal for trying!

Answer 30

bah, nonsense medal! I DON'T NEED YOUR PITY!!

^_^

Answer 31

He gave you a medal, be grateful LOL

Answer 32

its raining medals!

Answer 33

hahaha ^_^

Answer 34

It's raining GOLDDDDD CHOCOLATE COINS!!! /sugar rush/

Okay, I'll be done in a few. You can move on to the next problem in the mean-time (;

Answer 35

Make that 18 minutes ... curse this stupid sinus ache

Answer 36

for the second problem, find the acceleration needed to stop car with initial velocity of 35m/s in 1100m - I suggest the fourth equation of motion again

Then the force needed is the car's mass times this acceleration.

Answer 37

... Now you seriously deserve a medal.
But I can't give one D:

Answer 38

and the last one is just a ramp problem where you have to find theta



\[ F≥mg\sin \theta\]

solve for theta

Answer 39

\[F>mg\sin\theta\]

can't be equal to or the block won't go up the hill :p

Answer 40

It can be equal, if it's going at a constant velocity (i.e. You start pushing the block with a constant velocity before you're going up the slope, or something like that)

Answer 41

touchée

Answer 42

Also. I'm not sure that the weight force is equal to mg*sin(theta). I suck at trigonometry right now. :C

Answer 43

I show!!