How Do You Calculate Time from Velocity and Distance in Physics Problems?

[Buzur]

Homework Statement

A baseball pitcher is known to throw a pitch with a speed of 105 miles per hour. In how many seconds will the pitch reach the catcher if the mound is 20 meters away? (assume 1600 m in 1 mile)

Homework Equations

v=d/t

The Attempt at a Solution

Idk how to convert yet... I always cheat and use an online one but I will be screwed for the test... So I'm going to give this a try...

105 mi = 168000 m
1 hour = 3600 s

105 mi/h = 46.66 m/s

The other part of the question I am totally confuse on.
So i'll take the d/v=t?

20/46.66=0.4286s?


_____________________________________________________________________________

Homework Statement

A satellite travels at 4,000 km/hr. If the satellite travels 8 X 10^7 meters as it goes around once, how many hours are required for one orbit?

Homework Equations

v=d/t

The Attempt at a Solution

Honestly, I have never seen a problem with scientific notation except in math. I forgot how to do all that. So this one I honestly confuse on. How can I change that scientific notion to a number? I think that's what I need to do.

 

[Feodalherren]

The first one seems correct to me.

All 8 x 10^7 means is 8 x 10 x 10 x10 x10 x10 x10 x 10. So you take 10 and add 6 zeros. 6 zeros, not 7 because 10^1 = 10.
Now change it to km and you're good to go.

 

[rock.freak667]

Homework Statement

A baseball pitcher is known to throw a pitch with a speed of 105 miles per hour. In how many seconds will the pitch reach the catcher if the mound is 20 meters away? (assume 1600 m in 1 mile)

Homework Equations

v=d/t

The Attempt at a Solution

Idk how to convert yet... I always cheat and use an online one but I will be screwed for the test... So I'm going to give this a try...

105 mi = 168000 m
1 hour = 3600 s

105 mi/h = 46.66 m/s

The other part of the question I am totally confuse on.
So i'll take the d/v=t?

20/46.66=0.4286s?

That would be correct.

_____________________________________________________________________________

Homework Statement

A satellite travels at 4,000 km/hr. If the satellite travels 8 X 10^7 meters as it goes around once, how many hours are required for one orbit?

Homework Equations

v=d/t

The Attempt at a Solution

Honestly, I have never seen a problem with scientific notation except in math. I forgot how to do all that. So this one I honestly confuse on. How can I change that scientific notion to a number? I think that's what I need to do.

You can just multiply out that number to convert it into a 'normal' number. For example if you are given 43.1 x 10², this would be the same as 4310 i.e. you actually multiply the 43.1 by the 10² (which is 100)