Physics - October 2007

I noticed that there are two equations for speed and three for acceleration:

Speed:

1. Speed= distance/time

2.Average Speed= distance covered/time interval

How do I know which ones to use when solving a speed problem?

Acceleration:

1. A=change in velocity/time interval

2. A=change in speed/time interval

3. A=net force/mass

When solving an acceleration problem, how would I know which equation to use?

Please keep the explanations simple and add examples in necessary.

Thank you!!

2007-10-06 11:24:47 · 0 answers · asked by b 5

A car with a mass of 1200 kg is moving around a curve with a radius of 40 m at a constant speed of 20 m/n (about 45 MPH).

a. What is the centripetal acceleration of the car?
b. What is the magnitude of the force required to produce this centripetal acceleration?

2007-10-06 11:14:18 · 1 answers · asked by grtfulhdgirl 1

The fastest recorded pitch in MLB was thrown by Nolan Ryan in 1974. If this pitch were thrown horizontally....the ball would fall 0.809 m by the time it reached home plate, 18.3 m away.

The acceleration of gravity is 9.81 m/s2

How fast was Ryan's pitch? In m/s

2007-10-06 11:05:49 · 3 answers · asked by XzoeyX 2

A tennis player receives a shot with the ball (0.0600 kg) traveling horizontally at 58.0 m/s and returns the shot with the ball traveling horizontally at 34.0 m/s in the opposite direction. (Assume the initial direction of the ball is in the -x direction.)

(a) What is the impulse delivered to the ball by the racket?
5.52 N·s 0.0600(34 - (-58))=5.52

(b) What work does the racket do on the ball?
____J

Having trouble figuring out the work.

2007-10-06 11:04:45 · 2 answers · asked by burkehud 2

A dockworker loading crates on a ship finds that a 19 kg crate, initially at rest on a horizontal surface, requires a 84 N horizontal force to set it in motion. However, after the crate is in motion, a horizontal force of 50 N is required to keep it moving with a constant speed. Find the coefficients of static and kinetic friction between crate and floor.

2007-10-06 10:53:37 · 1 answers · asked by swimchic632 2

If you drop a ball from a certain height, were is the kinetic energy and potential energy? And how about the acceleration energy?

2007-10-06 10:44:16 · 2 answers · asked by snowflake 2

During a babseball game a batter hits a pop up to a fielder 72m away. The accleration of gravity is 9.8m/s2. If the ball reamins in the air for 6.2s, how high does it rise.

2007-10-06 10:36:48 · 1 answers · asked by Handiman 3

If a ball were tossed up with a spin, would gravity have little or no effect on the spin?

2007-10-06 09:51:10 · 7 answers · asked by Sky Guy 5

Seeing the world we are living in today is so widely saturated with wireless or cellular toys. Be it the phone, computer, radio,
television, and the list goes on. I have been wondering if one of these days the well-known insulated 'sparks' will become airborne also, not to mention being safe in the first place. On second thought, maybe some geniuses have already engineered the solution...

2007-10-06 09:19:01 · 7 answers · asked by DivCW 2

Monkey and the mirror... :) physics?

a massless rope is strung over a frictionless pulley. A monkey holds onto the rope, and a mirror having the same wieght as the monkey, is attached on the other side of the rope at the monkeys level. can the monkey get away from the image it sees in the mirror by....
(a) climbing up the rope
(b) climbing down the rope
(c) releasing the rope

explain...
for all the answers i put no. because the weight is the same, so there is same amount of tension and accleration...but the accleration is just in same magnitude but opposite direction. am i right? rather, is the explanation i provided right?
Additional Details

can the monkey get away from the image it sees in the mirror by....

2007-10-06 09:11:00 · 4 answers · asked by silyrabbittwixR4kidz 3

if any one please know any thing about it but please in scientific details and formulas if possible
even if you know any website that i can use except the wikpedia because i already read but i really need this subject asap and i need it to be very scientific and logic.
thanks alot

2007-10-06 08:27:06 · 2 answers · asked by 1101-1001 2

a massless rope is strung over a frictionless pulley. A monkey holds onto the rope, and a mirror having the same wieght as the monkey, is attached on the other side of the rope at the monkeys level.
(a) climbing up the rope
(b) climbing down the rope
(c) releasing the rope

explain...
for all the answers i put no. because the weight is the same, so there is same amount of tension and accleration...but the accleration is just in same magnitude but opposite direction. am i right? rather, is the explanation i provided right?

2007-10-06 07:45:26 · 2 answers · asked by silyrabbittwixR4kidz 3

2007-10-06 07:41:12 · 24 answers · asked by DARREN A 1

2007-10-06 06:31:38 · 2 answers · asked by zildjian4559 2

why does water (liquid) have a higher high specific capacity than steam (gas) and ice (solid) when all of them are made by the same elements?

2007-10-06 06:30:36 · 1 answers · asked by pdforta 2

2007-10-06 06:25:29 · 3 answers · asked by Baller T 1

2007-10-06 06:22:31 · 6 answers · asked by Danny M 1

I mean what if it's not?, does it change anything?

2007-10-06 06:10:46 · 7 answers · asked by Grg 2

)Calculate the gravitational potential of a point on the surface of the moon closest to the earth( ans : -3.9X10^6 J/kg)
Data : Mass of Earth : 6 X 10^24m
Mass of moon : 7.4 X 10^22m
radius of moon : 1.7 X 10^6 m
dist from centre of earth to centre of moon : 3.8 X 10^8m

what does it mean by a point on the surface of the moon closest to the earth?

if possible, do include a short statement of what the calculations involve. thanks alot!

2007-10-06 06:01:55 · 3 answers · asked by Anonymous

A 110 kg piano is placed on an incline of 35 degrees. the coefficient of friction between the piano and the incline is .13. What is the force of friction on the piano? What is the piano's acceleration down the incline?

im not sure what to do, for the force of friction i have two different answers, i got 80N and 114.79N.. i dont know if they're right.. then i have no idea how to figure out the acceleration..

please help!!

2007-10-06 06:01:51 · 1 answers · asked by Anonymous

I think I got this one right, just want to doublecheck is all. Thanks in advance!

A plane is flying in a loop to simulate weightlessness for a brief instant. If the speed is 215m/s, what is the radius of the circle?

I have since v = sqrt rg where v is velocity, r is the radius, and g is gravity, that it comes out to (215^2)/9.98 = 4631.7635m

Did I do this correctly? If not, please explain what I did wrong and get me on the right track. Thanks!

2007-10-06 05:58:46 · 3 answers · asked by mr_peepers810 5

A crate of mass 10.7 kg is pulled up a rough incline with an initial speed of 1.50 m/s. The pulling force is 190 N parallel to the incline, which makes an angle of with the horizontal. The coefficient of kinetic friction is 0.450, and the crate is pulled 4.40 m.

a) How much work is done by gravity?
b) How much mechanical energy is lost due to friction?
c) How much work is done by the 190 N force?
d) What is the change in kinetic energy of the crate?
e) ) What is the speed of the crate after it has been pulled 4.40 m?

2007-10-06 05:31:55 · 1 answers · asked by snow200098 2

Hey, can someone explain the relationship between linear and angular momentum. I know the equations p=mv (for linear momentum) and L=rp (for angular momentum). So how do i find out the linear speed of an object that's being spun around a center point. Say a disk of 500 kg of radius 1 meter being spun around once every second. So how do i find out the v in p=mv to find out the angular momentum ?
The simpler the help the more the thanks.

2007-10-06 05:10:11 · 1 answers · asked by David M 1

mmk so i have to know the normal temperature of hot water coming out of the faucet! like when you cant put your finger in the water cause its too hot. and also the really cold temp. of water coming out of the faucet. just the average, doesnt have to be real specific. k thx!

2007-10-06 04:39:49 · 2 answers · asked by flowerchild 4

The drawing shows a version of the loop-the-loop trick for a small car. If the car is given an initial speed of v = 3.9 m/s, what is the largest value that the radius r can have if the car is to remain in contact with the circular track at all times?

I tried doing

PE = KE
mgh = 1/2mv^2
2gh = v^2
2g(2r) = v^2
4gr = v^2
4(9.8) r = (3.9)^2

r = 0.388

but it was wrong. anybody helP?

2007-10-06 04:31:52 · 3 answers · asked by Alan W 2

Wood?
is that data collected?
a varible
or hypothesis?

2007-10-06 04:22:40 · 2 answers · asked by Halisha S 1

We know that fire is the biproduct of the rapid decomposition of a substance, such as wood. We also know how to use it, classify it based on it's heat and color, and handle it. But, *what is it*? What does fire itself consist of? With sophisticated enough technology, could we theoretically capture fire particles, or condense them into a liquid or a solid? What are actual fire particles, or are there any particles? Even light consists of photons, and all energy is essentially matter on one level or another.

2007-10-06 04:12:33 · 4 answers · asked by Michael F 3

A daredevil is shot out of a cannon at 45.0° to the horizontal with an initial speed of 26.0 m/s. A net is positioned a horizontal distance of 53.0 m from the cannon. At what height above the cannon should the net be placed in order to catch the daredevil?

2007-10-06 03:30:18 · 3 answers · asked by loveall 3

2007-10-06 03:20:28 · 8 answers · asked by =emelem_09= 2

If a person gets 99 times tails by tossing a coin, is it that the 100th time when he tosses the coin, it will be tails ?

Most of you will think that it is based on luck.

But, if we calculate mathematically, lets say we toss a coin 1000 times in vacuum and every time we toss it, it reaches the same height and with the same side of the coin every time.
Lets toss it from heads, now suppose we get tails on the first time, then by above conditions we must get tails every time we toss it.
By scientific thinking, we can say there is no such thing as luck.

What do you think ?

2007-10-05 23:40:01 · 7 answers · asked by Mikhil M 2