Maths help (it's easy for you guys)

[Dog--]

Ok, I'm in college level grade 12 Physics, and I haven't taken math in like 1.5 years, so I know this should be easy, but I am terrible at math, and suck even more at word problems.. I don't want the answers to these, just the formula, I'll solve that. Should be pretty basic (find X usually), there were actual questions (no words, but just numbers) that I solved easily. I just have a hard time translating from word to math, I solved some, but I'm going to post the ones that I just can't get.

A cattle train left Miami and travelled toward New York. 14 hours later a diesel train left travelling at 45km/h in an effort to catch up to the cattle train. After travelling for four hours, the diesel train finally caught up. What was the cattle trains average speed.

Jose left the White house and drove toward the recycling plant at an average speed of 40km/h. Rob left some time later driving in the same direction at an average speed of 48km/h. After driving for five hours Rob caught up with Jose. How long did Jose drive before Rob caught up?

A cargo plane flew to the maintenance facility and back. It took one hour less time to get there than it did to get back. The average speed on the trip there was 220mph. The average speed on the way back was 200mph. how many hours did the trip there take?

Kali left school and travelled toward her friends house at an average speed of 40km/h. Matt left one hour later and travelled in the opposite direction with an average speed on 50km/h. Find the number of hours Matt needs to travel before they are 400km apart.

Ryan left the science museum and drove south. Gabriella left three hours later driving 42km/h faster in an effort to catch up to him. After two hours Gabriella finally caught up. Find Ryan's average speed.

Chelsea left the white house and travelled toward the capital at an average speed of 34km/h. Jasmine left the same time and travelled in the opposite direction with an average speed of 65km/h. Find the number of hours Jasmine needs to travel before they are 59.4km apart.

A submarine left Hawaii two hours before an aircraft carrier. The vessels travelled in opposite directions. The aircraft carrier travelled at 25mph for nine hours. After this time the vessels were 280mi. apart. Find the submarines speed.

Jose left the airport and travelled toward the mountains. Kayla left 2.1 hours later travelling 35mph faster in an effort to catch up to him. After 1.2 hours Kayla finally caught up. Find Jose's average speed.

Thanks to anyone who helps, remember, I just need the formula, I'll do the rest.

And YES I KNOW IT'S EASY - this is exactly why I'm never taking math related class again.

/me waits for insults at my math skills.

Also, if you ask why I'm doing such easy math in grade 12 it's because it's the 3rd day of the new semester, this is supposedly review, and I've never taken physics before...

BTW, here's a few example of questions I had to do (so make them like this)

1) 6 = (a/4)+2

2) (n+5)/-16 = -1

I solved these, they're easy, it's just the translations between words and math that I suck at.

 

[Diesel_Power]

Jose's average speed is over 9000.

 

[Pesmerga]

Vegeta, what does it say about his power level?

ALSO DO YOUR OWN HOMEWORK

 

[TimoJay]

I don't want the answers to these, just tell me the answers in terms of X

fixed

 

[Dog--]

See, that's why I need help.


Fkn hate math.

 

[dfc05]

I'll just do the first one cause the rest seem similar. I hope my explanation makes sense.

A cattle train left Miami and travelled toward New York. 14 hours later a diesel train left travelling at 45km/h in an effort to catch up to the cattle train. After travelling for four hours, the diesel train finally caught up. What was the cattle trains average speed.

Make variables for all the info you're given and what you want to find out.
v(diesel) = velocity of diesel train
t(diesel) = time diesel has been traveling, when it catches up
d(diesel) = distance that the diesel train has traveled when it caught up
v(cattle), t(cattle), d(cattle) = same as above, but for the cattle train

Translate words to mathematical relationships:

(1) The diesel train left 14 hours later
--> t(cattle) = t(diesel) + 14 hr
(e.g. the cattle train has been traveling for 14 hours longer than the diesel train)

(2) The diesel train caught up in 4 hours
--> t(diesel) = 4 hr

combine (1) and (2) to get t(cattle)=18 hr

(3) The diesel and cattle train must have traveled the same distance to have caught up (they both went from Miami to exactly the same point down the rail line)
--> d(cattle) = d(diesel)

Now you need to relate distance, velocity, and time traveled:

d(cattle) = v(cattle) x t(cattle)
d(diesel) = v(diesel) x t(diesel)

Since they traveled the same distance (#3 above), then
v(cattle) x t(cattle) = v(diesel) x t(diesel)

You know v(diesel), t(cattle), and t(diesel), so you can solve for v(cattle)

In numbers, this comes out to be:
v(cattle) x 18 hr = 45 km/hr x 4 hr

 

[Adabiviak]

Jose's average speed is over 9000.

lol - that's almost worth writing as an answer.

 

[Dan]

A cattle train left Miami and travelled toward New York. 14 hours later a diesel train left travelling at 45km/h in an effort to catch up to the cattle train. After travelling for four hours, the diesel train finally caught up. What was the cattle trains average speed.

v_diesel = 45km/h
t_diesel = 4h
t_cattle = 14h + t_diesel

When the two trains meet, they have both traveled the same distance.

distance=velocity*time

dist_cattle = dist_diesel
v_cattle * t_cattle = v_diesel * t_diesel
v_cattle * (14h + t_diesel) = v_diesel * t_diesel
v_cattle = v_diesel * t_diesel / (14h + t_diesel)

Jose left the White house and drove toward the recycling plant at an average speed of 40km/h. Rob left some time later driving in the same direction at an average speed of 48km/h. After driving for five hours Rob caught up with Jose. How long did Jose drive before Rob caught up?

v_Jose = 40km/h
v_Rob = 48km/h
t_Rob = 5h

It's the same thing; distances are equal.

dist_Jose = dist_Rob
v_Jose*t_Jose = v_Rob*t_Rob
t_Jose = v_Rob / v_Jose * t_Rob

A cargo plane flew to the maintenance facility and back. It took one hour less time to get there than it did to get back. The average speed on the trip there was 220mph. The average speed on the way back was 200mph. how many hours did the trip there take?

t_there + 1h = t_back
v_there = 220mph
v_back = 200mph

dist_there = dist_back
v_there * t_there = v_back * t_back
v_there * t_there = v_back * (t_there + 1h)
v_there * t_there = v_back * t_there + v_back * 1h
(v_there - v_back) * t_there = v_back * 1h
t_there = v_back * 1h / (v_there - v_back)

Kali left school and travelled toward her friends house at an average speed of 40km/h. Matt left one hour later and travelled in the opposite direction with an average speed on 50km/h. Find the number of hours Matt needs to travel before they are 400km apart.

v_Kali = 40km/h
v_Matt = 50km/h
(these kids sure walk fast)

t_Kali = t_Matt+1h

dist_Kali +dist_Matt = 400km
v_Kali * t_Kali + v_Matt * t_Matt = 400km
v_Kali * (t_Matt + 1h) + v_Matt * t_Matt = 400km
v_Kali * t_Matt + v_Kali * 1h + v_Matt * t_Matt = 400km
(v_Kali + v_Matt) * t_Matt + v_Kali * 1h = 400km
t_Matt = (400 - v_Kali * 1h) / (v_Kali + v_Matt)

Ryan left the science museum and drove south. Gabriella left three hours later driving 42km/h faster in an effort to catch up to him. After two hours Gabriella finally caught up. Find Ryan's average speed.

t_Ryan = t_Gabe + 3h
v_Gabe = v_Ryan + 42km/h
t_Gabe = 2h

dist_Gabe = dist_Ryan
v_Gabe * t_Gabe = v_Ryan * t_Ryan
(v_Ryan + 42km/h) * t_Gabe = v_Ryan * (t_Gabe + 3h)
v_Ryan * t_Gabe + 42km/h * t_Gabe = v_Ryan * t_Gabe + v_Ryan * 3h
42km/h * t_Gabe = v_Ryan * 3h
v_Ryan = 42km/h * t_Gabe / 3h

Chelsea left the white house and traveled toward the capital at an average speed of 34km/h. Jasmine left the same time and traveled in the opposite direction with an average speed of 65km/h. Find the number of hours Jasmine needs to travel before they are 59.4km apart.

v_Chel = 34km/h
v_Jasm = 65km/h
dist_Jasm + dist_Chel = 59.4km
t_Jasm = t_Chel

v_Chel * t_Jasm + v_Jasm * t_Jasm = 59.4km
(v_Chel + v_Jasm) * t_Jasm = 59.4km
t_Jasm = 59.4 / (v_Chel + v_Jasm)

A submarine left Hawaii two hours before an aircraft carrier. The vessels travelled in opposite directions. The aircraft carrier travelled at 25mph for nine hours. After this time the vessels were 280mi. apart. Find the submarines speed.

t_sub = t_car + 2h
v_car = 25mph
t_car = 9h

dist_car + dist_sub = 280mi
v_car * t_car + v_sub * t_sub = 280mi
v_car * t_car + v_sub * (t_car + 2h) = 280mi
v_sub = (280mi - v_car * t_car) / (t_car + 2h)

Jose left the airport and traveled toward the mountains. Kayla left 2.1 hours later traveling 35mph faster in an effort to catch up to him. After 1.2 hours Kayla finally caught up. Find Jose's average speed.

t_Jose = t_Kayla + 2.1h
v_Kayla = v_Jose + 35mph
t_Kayla = 1.2h

dist_Jose = dist_Kayla
v_Jose * t_Jose = v_Kayla * t_Kayla
v_Jose * (t_Kayla + 2.1h) = (v_Jose + 35mph) * t_Kayla
v_Jose * t_Kayla + v_Jose * 2.1h = v_Jose * t_Kayla + 35mph * t_Kayla
v_Jose * 2.1h = 35mph * t_Kayla
v_Jose = 35mph * t_Kayla / 2.1h

 

[highlander]

this thread makes me feel so dumb

 

[AJ Rimmer]

this thread makes me feel so dumb

Join the club.

 

[Kula Meenur]

0.99999999rec = 1 ?

 

[Solaris]

Wow, nice to see everyone being to helpful, makes me smile.

 

[PJ]

Jose's average speed is over 9000.

lol.

i'm in year 9 (UK) and i'm doing simpler versions of this sort of stuff.

always remember the triangle thing:

just cover up the one you want to find. eg D=S*T, T=D/S

EDIT: i know this is so basic. meh

 

[Pesmerga]

D+SxT

lolwut

Also, don't ever use 'x' to represent multiply. Also, triangles are for kids.

 

[swan_song1973]

Jose's average speed is over 9000.

you know your shit.

 

[PJ]

lolwut

Also, don't ever use 'x' to represent multiply. Also, triangles are for kids.

fixed. meh.

 

[cleverendeavouR]

From my experience from high school and even college, the review is ALWAYS harder than when you start doing it during the semester.


Once you get some background knowledge (or have previous knowledge refreshed) it all gets easier.