Physics - February 2007

also does anyone know these other questions, When does frictional force occur?

It takes a minimuum force of 280 N to move 50 kilo crate. Whats the coefficent of maximum static friction between the crate and floor?

Force created when you re pushing something at rest, you must overcome, ____to move object.(the name of that force?)

static frictional force is _____________
angle of resultant vector is _____________
kinnetic frictional force is _____________

thanks!

2007-02-22 12:49:26 · 1 answers · asked by nice too meet you. 4

A coin is placed on a record that is rotating at 33.3 rpm. If the coefficient of static friction between the coin and the record is 0.2, how far from the center of the record can the coin be placed without having it slip off?

Ok, I thought I needed to use the equation V=sqrt(Msgr). Ms=static friction. I converted 33.3rpm into rad/s and solved for r. But my answer just isn't coming out right. Any tips??
Am I even using the correct equation??

Thank you so much in advance!

2007-02-22 12:43:17 · 1 answers · asked by Anonymous

1) A race car has a mass of 718 kg. It starts from rest and travels 44.0 m in 3.0 s. The car is uniformly accelerated during the entire time. What net force is exerted on it?
N=?

2)Your mass is 80 kg. You stand on a bathroom scale in an elevator on Earth.

(a) What force would the scale exert when the elevator moves up at a constant speed?
N=?
(b) What force would the scale exert when it slows at 2.2 m/s2 while moving upward?
N=?
(c) What force would the scale exert when it speeds up at 2.2 m/s2 wile moving downward?
N=?
(d) What force would the scale exert when it moves downward at a constant speed?
N=?
(e) What force would the scale exert when it slows to a stop at a constant magnitude of acceleration?



3) A boy exerts a 38 N horizontal force as he pulls a 54 N sled across a cement sidewalk at constant speed. What is the coefficient of kinetic friction between the sidewalk and the metal sled runners? Ignore air resistance.

2007-02-22 12:42:30 · 2 answers · asked by mommy 3

What does E=MC2 actually mean? How does it work? Also, does it have anything to do with Einstien's theory that time can be slowed (maybe even stopped)?

Do you know of any websites where I can learn more about this?

2007-02-22 12:41:51 · 5 answers · asked by Lost_Lady 3

if you release the brake and then push as hard as you can on the steening whell, why won't the car move?

2007-02-22 12:23:55 · 5 answers · asked by Anonymous

a force that puts an object at equilibruim is ________

When does frictional force occur?

It takes a minimuum force of 280 N to move 50 kilo crate. Whats the coefficent of maximum static friction between the crate and floor?

Force created when you re pushing something at rest, you must overcome, ____to move object.(the name of that force?)

static frictional force is _____________
angle of resultant vector is _____________
kinnetic frictional force is _____________

thanks!

2007-02-22 12:14:10 · 1 answers · asked by nice too meet you. 4

I think Albert Einsten had two children with his first marriage. I am curious to know if his genes are being carried.

2007-02-22 12:04:10 · 3 answers · asked by David Conrad 1

2007-02-22 11:59:41 · 1 answers · asked by emad a 1

That is, if objects on Earth accelerate at 9.8m/s^2. I don't understand this at all. Someone please help and thoroughly explain it to me, thanks. :)

... darn physics..

2007-02-22 11:57:37 · 5 answers · asked by herbritannicmajesty68 3

hello I have a few questions
thankyou!

1) Calculate the force you exert as you stand on the floor assuming you weigh 180 lb. (1 lb = 0.454 kg).

2)A dragster starts with zero velocity and completes a 402.1 m (0.2513 mile) run in 4.910 s. If the car had a constant acceleration, what would be its acceleration and final velocity?
m/s2 =?
m/s=?

3)After a day of testing race cars, you decide to take your own 1460 kg car onto the test track. While moving down the track at 10.0 m/s, you uniformly accelerate to 32.0 m/s in 10 s. What is the average net force that you have applied to the car during the 10 s interval?
N=?
n is newtons

4)A race car has a mass of 718 kg. It starts from rest and travels 44.0 m in 3.0 s. The car is uniformly accelerated during the entire time. What net force is exerted on it?
N=?

5)Your mass is 80 kg. You stand on a bathroom scale in an elevator on Earth.

(a) What force would the scale exert when the elevator moves up at a constant speed?
N=?
(b) What force would the scale exert when it slows at 2.2 m/s2 while moving upward?
N=?
(c) What force would the scale exert when it speeds up at 2.2 m/s2 wile moving downward?
N=?
(d) What force would the scale exert when it moves downward at a constant speed?
N=?
(e) What force would the scale exert when it slows to a stop at a constant magnitude of acceleration?



6) A boy exerts a 38 N horizontal force as he pulls a 54 N sled across a cement sidewalk at constant speed. What is the coefficient of kinetic friction between the sidewalk and the metal sled runners? Ignore air resistance.



thankyou for the help everyone!

2007-02-22 11:57:03 · 3 answers · asked by mommy 3

If one could transport a simple pendulum of constant length from the Earth's surface to the Moon's, where the acceleration due to gravity is one-sixth (1/6) that on the Earth, by what factor would the pendulum frequency be changed?

a. about 6.0
b. about 2.5
c. about 0.41
d. about 0.17

2007-02-22 11:33:58 · 1 answers · asked by Tennis2127 2

I need an idea for a report. The report is suppose to be a misconception that young children have about physics. (gravity, inertia, forces of motion...) any thoughts??

2007-02-22 11:27:19 · 4 answers · asked by platypus 2

You have been asked to design a "ballistic spring system" to measure the speed of bullets. A bullet of mass 2.90 g is fired into a block of mass 1.80 kg. The block, with the embedded bullet, then slides across a frictionless table and collides with a horizontal spring whose spring constant is k=32.0 N/m. The opposite end of the spring is anchored to a wall. What was the speed of the bullet if the spring's maximum compression is 14.4 cm?

2007-02-22 11:01:27 · 1 answers · asked by N 1

To help keep his barn warm on cold days, a farmer stores 890 kg of solar-heated water (Lf = 3.35 105 J/kg) in barrels. For how many hours would a 1.0-kW electric space heater have to operate to provide the same amount of heat as the water does, when it cools from 10.0 to 0.0°C and completely freezes?

i am really confused what to do. i thought that the 1.0 kW was work, which equals q/t. so i solved for q by adding the q that it would take to get to zero and the q for fusion. BUT when i went to solve for t i got a negative answer. so i know it must be wrong. and redid it and got a huge number. any advice on how to take this problem?

2007-02-22 10:56:49 · 3 answers · asked by lifewithgooli 1

Two astronauts, of masses 60.0 kg and 80.0 kg, are initially at rest in outer space. They push each other apart. What is the separation after the lighter astronaut has moved 12meters?

2007-02-22 10:51:51 · 2 answers · asked by mrsmoan92 3

1) Determine the inductive reactance of a 10.0 mH coil connected to a 100 Hz ac generator.

2) A capacitor with a reactance of 100 Ohms is in series with a 100 Ohm resistor. The ac voltage across the two:
a)leads the current by 45°
b)lags the current by 45°
c)none of these
d)lags the current by 90°
e)leads the current by 90°

My initial guesses are:
1)6.28 Ohms
2) C

2007-02-22 10:36:05 · 1 answers · asked by Jake D 2

2007-02-22 10:28:29 · 2 answers · asked by swimmertommy 1

and the other three are asymmetric .For one mole of CO2,(10^24 molecules),calculate the number of ways that the CO2 can be evenly distributed among these four vibrational modes.
Calculate the entropy of this state.
Compare this result witth the entropy of a state in which all 10^24 molecules are in a single vibrational mode.
Hint:using Sterling's approximation is handy

2007-02-22 10:17:40 · 1 answers · asked by zizi m 1

2007-02-22 10:08:32 · 5 answers · asked by emad a 1

2007-02-22 09:54:29 · 4 answers · asked by Brian S 2

2007-02-22 09:51:18 · 2 answers · asked by Killa 1

To help keep his barn warm on cold days, a farmer stores 890 kg of solar-heated water (Lf = 3.35 105 J/kg) in barrels. For how many hours would a 1.0-kW electric space heater have to operate to provide the same amount of heat as the water does, when it cools from 10.0 to 0.0°C and completely freezes?
__________ hours


i am really confused what to do. i thought that the 1.0 kW was work, which equals q/t. so i solved for q by adding the q that it would take to get to zero and the q for fusion. BUT when i went to solve for t i got a negative answer. so i know it must be wrong. and redid it and got a huge number. any advice on how to take this problem?

2007-02-22 09:41:14 · 2 answers · asked by lifewithgooli 1

A charging RC circuit controls the intermittent windshield wipers in a car. The emf is 12.0V. The wipers are triggered when the voltage across the 125(micro)F capacitor reaches 10.0V; then the capacitor is quickly discharged (through a much smaller resistor) and the cycle repeats. What resistance should be used in the charging circuit if the wipers are to operate once every 1.80s?

2007-02-22 09:09:04 · 1 answers · asked by iansbaby17 3

2007-02-22 09:03:53 · 1 answers · asked by DIVA1 1

2007-02-22 09:02:57 · 5 answers · asked by DIVA1 1

A piece of copper wire is formed into a single circular loop of radius 9 cm. A magnetic field is oriented parallel to the normal to the loop, and it increases from 0 to 0.45 T in a time of 0.45 s. The wire has a resistance per unit length of 3.3 10-2 /m. What is the average electrical energy dissipated in the resistance of the wire.

2007-02-22 09:00:01 · 2 answers · asked by christian m 2

In physics we're doing a unit over circular motion and I'm so confused. I don't understnad it at all. Could you please explain these to me? Thanks!

In a carnival the "Spinner of Death" is a ride where all the participants stand in metal reinforced ring with diameter of 10m. THe ride then accelerates the ring to a certain angular velocity such that the participants are pressed against the wall. THe floor of the ride is then dropped and the participants remain pressed agains the wall. Coefficeint of friction is .5. a) What angualr velocity must the ride achieve in order to keep the participants from falling off the ride? b) If the floor falls after 2 minutes, what must angular acceleration be in order for this to happen?

A 100,000 N truck takes a curve w/ a radius of 200m. The truckis traveling 75 km/h and coefficient of friction at that spot is .09. Will the truck remain on the road or slide off? Why or why not.

Thank you for any explanations.

2007-02-22 08:57:44 · 3 answers · asked by Anonymous

I know its debatable, but what do you think?

2007-02-22 08:55:16 · 12 answers · asked by hmbn 4

I read from some websites that some subatomic particles are produced during proton - antiproton annihilation, but I don't know what are the names of those subatomic particles. Please help me!

2007-02-22 08:52:35 · 2 answers · asked by Suhel 1

2007-02-22 08:52:24 · 6 answers · asked by becky.elmes@btinternet.com 1