Hey taks, aren't you good at physics? Maybe Meta?

[thepixiesrock]

A bowling ball traveling with constant speed hits the pins at the end of a bowling lane 16.5m long. The bowler hears the sound of the ball hitting the pins 2.50 seconds after the ball is released from his hands. What is the speed of the ball? the speed of sound is 340m/s.

 

How do I do this?

Edited September 10, 2006 by thepixiesrock

[metadigital]

Take off the sound bit.

 

∴ 2.5 seconds (total time) take away 16.5

[Surreptishus]

High school problem so i am assuming closed system and bowling lane is smooth etc.

 

2.5s= time for sound to travel to bowler+ time for ball to hit the pins.

 

^ if thats right it should be a big hint.

 

edit: crap i got beat by meta. Well i was trying to help pixies work it out for himself.

Edited September 10, 2006 by Surreptishus

[thepixiesrock]

Hey, thanks.

[thepixiesrock]

At highway speeds, a particular automobile is capable of an acceleration of about 1.6m/s^2. At this rate, how long does it take to accelerate from 80 km/h to 110 km/h?

 

So like, something along the lines of 110-80= 30km/h, and then do something with the 1.6 m/s?

 

So how long does it take him to accelerate a velocity of positive 30 km/h, if he accelerates 1.6 meters every second?

 

How long does it take him to accelerate a velocity of positive 8.34 m/s, if he accelerates 1.6 meters every second?

 

8.34/1.6 = 5.215 seconds.

 

Is that right? Or did I go wrong somewhere? Because I'm really having trouble focusing right now.

[Surreptishus]

Do you know equations of motion?

[metadigital]

Nearly. The car is accelerating every second by an additional 1.6m. (1.6 meters per sec per sec)

 

So, not devided by 1.6, you need to use:

where

 

u is the initial velocity (m/s)

v is the final velocity (m/s)

t is the time interval (s) elapsed between the two velocity measurements (also writen as "Δt")

[Surreptishus]

Also conevrt everthing into the same units. Convert the velocities into m/s.

[Bokishi]

Meta you should charge pixies for this information.

[thepixiesrock]

So: 30.58m/s - 22.24m/s = 8.34 m/s, therefore; 1.6m/s^2= 8.34m/s divided by time?

 

I'm a moron, I don't know what to do next. I can't focus.

[Nick_i_am]

Guys! Do my homework too!

[thepixiesrock]

Sure, but at least I'm not just asking for the answer, I was asking how to do it. I'm trying to learn Nick. Stop pestering me.

[LostStraw]

According to Meta's equation, you were right the first time.

 

a = (v - u) / t

 

solving for t:

 

t = (v - u) / a

 

putting the numbers in:

 

t = (30.6m/s - 22.2m/s) / 1.6m/s/s

 

with rounding errors > 5.25s

[thepixiesrock]

Yeah, I know that now.

[Nick_i_am]

Sure, but at least I'm not just asking for the answer, I was asking how to do it.  I'm trying to learn Nick.  Stop pestering me.

<{POST_SNAPBACK}>

 

It was a simple request, you don't have to be rude

[Tigranes]

No, we're not doing your arithmetic for you, nick.

[Colrom]

Meta's solution is elegant.

 

I liked Meta's approach. He starts with the important stuff and makes a minor adjustment. He makes it easy to see that the adjustment is minor.

 

Nice!

[Cantousent]

Okay, make the kid do his own work, folks! :Cant's reproachful grin icon:

[taks]

i've been studying all day. a quick glance says everything is fine... nothing to see here, move along.

 

taks

[Arkan]

PHY101 stuff, really.

[taks]

yeah, the actual derivations for the equations (using calculus, derivatives) are college level, but high-school physics does spend a lot of time on the actual equations.

 

my high-school physics class was a blast. the teacher was one i'll never forget...

 

taks

[Lucius]

Math is the work of the devil, someone summon Eldar! We need to banish the daemon! :ph34r:

[Atreides]

In before someone divides by 0.

[6 Foot Invisible Rabbit]

Guns don't kill people. Physics kill people.

[taks]

dividing by zero is a legitimate function unless the dividend is also zero.

 

taks