# Speed, a.k.a. Velocity

by Dustin Glazier and Josh Patrice, January 1998

## 1.

A car in front of the school goes 30.0 m in 2.35 seconds. What is its speed?

( 12.8 m/s)
Here is what you start with:
- X = 30 m
- t = 2.35 sec
- V = ?

Try to put those numbers into formulas
V = (30 m)/ (2.35 sec)
We quickly find that V = 12.8 m/s
Josh: Just another useless tedious task setup by the schools to suck away our lives.
Dustin: Yeah, but in a fun way! Table of Contents

## 2.

What time will it take a car going 88 f/s to go 13 feet?
(.15s)
Here is what you start with:
- X = 13 ft
- t = ?
- V = 88 f/s

Plug those parts in and see what we get.
t = (13 ft)/(88 f/s)
t = .147727 or .15 seconds
Go to:Table of Contents

## 3.

My Jetta can go 92 f in about 1.35 seconds. What is its speed?
(68 ft/sec)
Here is what you start with:
- X = 92 ft
- t = 1.35 seconds
- V = ?

I'm going to go out on a limb and say "try putting it in a formula"
V = (92 ft)/(1.35 sec)
V = 68 ft/sec
Dustin: You know Josh, it's a very nice Jetta.
Josh: Aww, well I wanted an M1 Abrahms tank, but the
dealership was all out, so I settled for it.
Go to: Table of Contents

## 4.

What is the speed of my Jetta from problem 3 in miles/hour? What is it's color?
(46 mph, Red)
Here is what you start with:
- X = 92 ft
- t = 3.2 seconds
- V = 68 ft/sec

This is just conversion.
As we already know, there are 3600 seconds in an hour and 5280 feet in a mile
so we then multiply 68 by 3600
so 68 feet x 3600 sec
------- ----------
1 sec 1 hour
the seconds cancel out leaving feet per hour
and then divide by 5280
so 244800 feet x 1 mile
----------- ----------
1 hour 5280 feet
This gives you miles per hour
And V = 46 mph
Josh: Listen, I was the first person at school with a Red Jetta and it's red because I like it.
Dustin: Yeah cause it makes it look like a Raisin!
Josh: A WHAT!
Dustin: A reallllyyyy cool Raisin?
Josh: Dustin, Raisin's aren't red!
Dustin: Yeah, but if they were, your car could look like one!
Go to:Table of Contents

## 5.

A glazier moves at a rate of 5.6 feet/day. What distance does he go in two weeks?
()
Here is what you start with:
- X = ?
- t = 2 weeks or 14 days
- V = 5.6 feet/day

PUT THE NUMBERS IN A FORMULA!!!!
X = (14 days)(5.6 ft/days)
X = 78.4 feet
Josh: Do you really move that little?
Dustin: No, not always!
Josh: I should hope not.
Dustin: Sometimes less if I'm close to the refrigerator.
Go to: Table of Contents

## 6.

A trucker goes 345 miles in 7.0 hours. What is her speed?

( 49 mph)
Here is what you start with:
- X = 345 miles
- t = 7 hours
- V = ?

Uhh, use those great formulas and work that physics magic
V = (345 miles)/ (7 hours)
Math yields the answer of 49 miles per hour or mph.
Go to: Table of Contents

## 7.

A space shuttle moves at 3.4 miles/second. What distance does it go in one hour? How many feet?
Here is what you start with:
- X = ?
- t = 1 hr
- V = 3.4 miles/sec

We first break 1 hour down into seconds, there are 60 minutes in an hour and 60 seconds
therefore 3600 seconds in 1 hour.
Josh: And how many people wasting their time on this web page?
Dustin: Just us two, Josh.
Plug those parts in and see what we get.
X = (3600 sec)(3.4 miles/sec)
X = 12240 miles
However, Mr. Murray seems hell bent on using feet, so we must convert
Now, there are 5280 feet in a mile, so (12240 ft)(5280 ft/ mile)
And X = 64627200 feet or 6.5 x 10^{7}feet
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## 8.

A car moving 44 feet/second takes what time to travel 16 feet?
(.36 s)
Here is what you start with:
- X = 16 ft
- t = ?
- V = 44 ft/s

Well let's find time:
Dustin: 10:45
Josh: No, moron. The time it takes to travel 16 feet!
Dustin: Oh, yeah.
V = X/t
(44) = (16)/t
t = (.36s)
Go to: Table of Contents

## 9.

What speed must you average to go 280 km in 3.0 hours(93 km/h)
Here is what you start with:
- X = 280 km
- t = 3.0 hrs
- V = ?

Dustin: This problem is quite simple.
Josh: All the problems are quite simple.
Dustin: Uhh, yes but this one is even simpler!
V = (280)/(3.0)
V = (93 km/h)
Go to:Table of Contents

## 10.

A river current moves at 3.2 miles/hour. How many seconds will it take you to drift 45 feet? (Convert to feet/second first)(9.6 s)
Here is what you start with:
- X = 45 ft
- t = ?
- V = 3.2 mi/h

First, let's convert the velocity to feet/seconds.
As we learned before,
so 3.2 miles x 1 hour
------- ----------
1 hour 3600 sec
the hours cancel out leaving miles per second
and then divide by 5280
so 3.2 miles x 5280 feet
----------- ----------
3600 sec 1 mile
This gives you feet per second
And V = 4.69 ft/sec
t = (45)/(4.69)
t = (9.6s) Table of Contents

## 11.

Convert 45 miles/hour to Feet/second? (66 f/s)
If this has begun to look familiar to you, you're not alone
so 45 miles x 1 hour
------- ----------
1 hour 3600 sec
the hours cancel out leaving miles per second
and then divide by 5280
so 45 miles x 5280 feet
----------- ----------
3600 sec 1 mile
This gives you feet per second
(66 f/s)
Josh: Boy I wish I had that tank.
Dustin: You are a small, small man. And you have my pity, farewell.
Go to: Table of Contents

## 12.

Convert 60 km/hour to m/s? (17 m/s)
Boy oh boy another conversion problem!
all right 60 kilos x 1 hour
---------- ---------
1 hour 3600 sec
this gives us km/sec
so 60 kilos x 1000 meters
---------- --------------
3600 sec 1 kilo
thus giving us m/s.
In fact this gives us (17m/s).
Josh: Dustin?! Dustin?! Where have you gone? I feel so alone.
Go to: Table of Contents

## 13.

Convert 80 feet/second to m/s?(24 m/s)
Josh: Dustin?
Dustin: Yes.
Josh: Where have you been?
Dustin: That is none of your concern little boy. And I'll thank you to stay out of my personal affairs.
Josh: How do we do this problem?
Dustin: The kids should just use their magical powers to make it wind up to be 24m/s.
Josh: Well, you heard the man.
Go to: Table of Contents

## 14

A car in front of the school travels 15 feet in .38 seconds. What is its speed in m/s?(12 m/s)
Here is what you start with:
- X = 15 ft
- t = .38 sec
- V = x

Hey kids, guess what. We need to convert this bad boy into m/s.
V = 15 ft x 9.8 m
--------- --------
.38 sec 32 ft
So,
this leaves us with 12.09m/s
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## 15

A satellite travels at 5.4 miles in 3.2 seconds. What is its speed in miles/hour?(6075 mph)
Here's what we have:
- X = 5.4 miles
- t = 3.2 sec
- V = x

Simply multiply 5.4 by 3600 to obtain hours.
Then,
V = (19440)/(3.2)
V = (6075 mph)
Josh: Hey, Dustin, it's done!
Dustin: What's done?
Josh: The physics page.
Dustin: Cool. So what do we need to finish?
Josh: Nothing other than 4 months of late physics homework, the page is done.
Dustin: Cool. So what do we need to finish?
Josh: NOTHING,THE PAGE IS DONE!!!
Dustin: Cool. So what do we need to finish?
Josh: NO, YOU DON'T UNDERSTAND, IT'S ALL DONE!!!
Dustin: What, what's done?
Josh: THE BLOODY WEB PAGE!!!!
Dustin: We did a web page?
Josh: Who's on the what now?
Dustin: Oh, yeah!
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