# Math Is Fun Forum

Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫  π  -¹ ² ³ °

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## #1 2021-04-11 12:38:13

mathland
Banned
Registered: 2021-03-25
Posts: 438

### Velocity

At a certain instant, the speedometer of an automobile
reads V mi/h. During the next 1/4 s the automobile travels 20 ft.
Estimate V from this information.

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## #2 2021-04-11 19:27:21

Bob
Registered: 2010-06-20
Posts: 9,128

### Re: Velocity

speed = distance / time

B

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

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## #3 2021-04-12 10:27:49

mathland
Banned
Registered: 2021-03-25
Posts: 438

### Re: Velocity

Bob wrote:

speed = distance / time

B

At a certain instant, the speedometer of an automobile
reads V mi/h. During the next 1/4 s the automobile travels 20 ft.
Estimate V from this information.

Distance = 20 feet

Time = (1/4)s

Is the formula V = 20/(1/4)s miles per hour?

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## #4 2021-04-12 19:59:21

Bob
Registered: 2010-06-20
Posts: 9,128

### Re: Velocity

Arh! Good question.

The units for V are determined by what units are used for D and T.  So if you do 20/0.25 you have the velocity in ft / s.

To get an answer in mph  you'll have to do the conversions.

20 ft converts to  20/(3 x 1760) miles and 0.25 s converts to  0.25/3600 hours.

Bob

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

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## #5 2021-04-14 11:55:39

mathland
Banned
Registered: 2021-03-25
Posts: 438

### Re: Velocity

Bob wrote:

Arh! Good question.

The units for V are determined by what units are used for D and T.  So if you do 20/0.25 you have the velocity in ft / s.

To get an answer in mph  you'll have to do the conversions.

20 ft converts to  20/(3 x 1760) miles and 0.25 s converts to  0.25/3600 hours.

Bob

Very good. Not too bad. Interesting question.

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