Math Is Fun Forum

mathland

Member

Registered: 2021-03-25

Posts: 444

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.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,640

Re: Velocity

speed = distance / time

B

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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

mathland

Member

Registered: 2021-03-25

Posts: 444

Re: Velocity

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?

Bob

Administrator

Registered: 2010-06-20

Posts: 10,640

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

mathland

Member

Registered: 2021-03-25

Posts: 444

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

Very good. Not too bad. Interesting question.