Physics - October 2007

You are driving to the grocery story at 20 m/s. You are 110 m from an intersection when the traffic light turns red. Assume that your reaction time is 0.50 s and that your car brakes with constant acceleration.

a. How far are you from the intersection when you begin to apply the brakes?
b. What acceleration will bring you to rest right at the intersection?
c. How long does it take you to stop after the light changes?

Am I supposed to use equations and plug the numbers at the beginning of the question into whichever equations they may be? There are three different kinematic equations for motion with constant acceleration. Would I use one of them. I am not quite sure which to use if I am to use them.

2007-10-04 01:03:17 · 1 answers · asked by Brian 1

Imagine a person floating in space(vacuum). If he fires a rocket launcher in space, both the rocket and the man will move in opposite direction with a certain velocity. However, will the man and the rocket travel in space forever?

2007-10-03 21:03:22 · 7 answers · asked by ninjatortise 2

Lol, me again, Ok so I've been working on this problem for about 20 min and I CAN'T get it ): I bet it's easy :/ So the question is a average huffamoose has a mass of 3400kg. How many mg? Now this is Dimensional Analysis. I need explanation. Thanks so much (:

2007-10-03 18:56:37 · 3 answers · asked by Jazzy 1

Thanks, please include all steps so I can see how you got it.

2007-10-03 18:21:35 · 5 answers · asked by Anonymous

Alright this question uses the same exact formula, except both answers didn't explain the formula completely...

Here is the formula from my last question
"Formula for distance covered, s, is
s = ut + (1/2)at^2, where u = initial velocity and a = acceleration.
Here, u = 0 and a = 1.8 m/s^2
So, s = 0 + (1/2)(1.8)(1^2)
= 0.9 m."

^***What is the (1/2) for?***^

Here is the VERY similar question:

"A child slides down a hill on a toboggan with an acceleration of 1.8 m/s^2.

If she starts at rest, how far has she traveled in 2.0 s?"

So this is what I'd think you would plug in for the function

0 + (1/2)(1.8)(2^2), but it isn't correct and I still don't know what the (1/2) is.

2007-10-03 18:09:28 · 1 answers · asked by Anonymous

Because momentum is conserved, why?

2007-10-03 17:54:37 · 3 answers · asked by palishnayne 1

mass than the ball, why?

2007-10-03 17:53:23 · 3 answers · asked by palishnayne 1

Best answer = 10 points!

A child slides down a hill on a toboggan with an acceleration of 1.8 m/s^2.

If she starts at rest, how far has she traveled in 1.0 s?

I got 1.8 m but it was incorrect... how?

2007-10-03 17:40:13 · 3 answers · asked by Anonymous

(a). height of ballon at the end of 39 sec?
(b).Average velocity between t=0 and t=39?
(c).velocity of ballon at end of 39 sec?

2007-10-03 16:32:25 · 1 answers · asked by Anonymous

2007-10-03 16:11:09 · 2 answers · asked by rhynx 1

A 0.700 kg ball is on the end of a rope that is 2.00 m in length. The ball and rope are attached to a pole and the entire apparatus, including the pole, rotates about the pole's symmetry axis. The rope makes an angle of 70.0° with respect to the vertical as shown. What is the tangential speed of the ball?

I have a picture of this situation if you need it and I can email it to you if you let me know.

Thank you so much for any help. This is the only problem left that I just can't figure out.

2007-10-03 16:04:37 · 2 answers · asked by Physics 1

With theories like a Wave structure for matter that can explain basic function of atoms, why do we not hear about them in school?

Why is there such a wide held belief that an ether does not exist and that everything is particle basis?

2007-10-03 15:39:56 · 4 answers · asked by Zaarix 2

strange physics question.. lol

as a part of a larger problem i need to convert 6.0m/s into g's. and one g = 9.8m/s^2.

to be honest im not sure if its even possible lol if i had 6m/s^2 it would obviously be easy, but i just dont know about this one!

help!

2007-10-03 15:34:56 · 2 answers · asked by Anonymous

laws are made to be broken right

2007-10-03 15:24:54 · 7 answers · asked by dallas j 2

2007-10-03 15:20:17 · 3 answers · asked by Lim S 3

Even though the room behind is not loud at all when you open it?

2007-10-03 15:17:57 · 2 answers · asked by anonymous 4

2007-10-03 15:15:53 · 8 answers · asked by phillyfan11 1

I am so lost in this class...if anyone knows how to do this I would really appreciate it. Thanks=]

QUESTION:
You're a pilot on an aircraft carrier. You must fly to another aircraft carrier, now 1450 km at 45 degrees of your position, moving 56 km/h due east. The wind is blowing from the south at 72km/h. Calulate the heading and air speed needed to reach the carrier 2.5h after you take off....HINT: Draw a displacement vector diagram.

2007-10-03 15:15:14 · 1 answers · asked by Danielle 2

my english teacher said its possible to break glass without it making a sound. No one in my class knows how and neither do I. He said he knew how and whoever was to get it right got extra credit. so does anyone on here know how to do this? cause i could really use the extra credit in his class. thx guys!

2007-10-03 15:03:28 · 9 answers · asked by ']['.(()).]])). 1

The acceleration is 4 m/s^2. What is the coefficient of friction?

2007-10-03 14:54:20 · 1 answers · asked by steve paisley 2

How could you determine the mass of an object if you were in a space shuttle?

You do not know the density, or the mass of the object on earth.
Please help me. The sooner you answer, the more likely I will choose your answer as the best answer.

2007-10-03 14:50:02 · 3 answers · asked by koolkid23 2

Please explain. Your help is greatly appreciated.

2007-10-03 14:28:04 · 5 answers · asked by koolkid23 2

A long, straight wire carrying a current of 959 A is placed in a uniform magnetic field whose magnitude is 8.76x10-3 T. The wire is perpendicular to the field. Find a point in space where the net magnetic field is zero. Locate this point by specifying its perpendicular distance from the wire.

Not sure what equation to use.

2007-10-03 14:27:56 · 1 answers · asked by Jeff T 1

Two circular loops of wire, each containing a single turn, have the same radius of 9.71 cm and a common center. The planes of the loops are perpendicular. each carries a current of 6.84 A. What is the magnitude of the net magnetic field at the common center?

Lost, any help would be appreciated. Thanks

2007-10-03 14:25:50 · 2 answers · asked by Jeff T 1

1. At what horizontal velocity would a satellite have to be launched from the top of Mt. Everest to be placed in a circular orbit around the Earth?

=.............m/s

2. During an Apollo lunar landing mission, the command module continued to orbit the Moon at an altitude of about 148 km. How long did it take to go around the Moon once?
=.........s

3. What is the distance from the Earth's center to a point outside the Earth where the gravitational acceleration due to the Earth is 1/38 of its value at the Earth's surface?
=.............m

2007-10-03 14:24:39 · 2 answers · asked by Nikita 1

A car is traveling at 58.0 km/h on a flat highway. If the coefficient of friction between road and tires on a rainy day is 0.100, what is the minimum distance in which the car will stop?

I thought i needed mass to find the coefficient, but the problem doesn't give it...

2007-10-03 14:19:32 · 1 answers · asked by BMac 3

A 6g bullet is fired horizontally into a 2.8 kg block resting on a horizontal surface with a coefficient of friction of .3. When the bullet comes to rest in the block, the block has slid .65m. What is the velocity of the bullet?

the answer is 915 m/s but i don't know how to solve the problem.

2007-10-03 13:59:57 · 2 answers · asked by Pife 2

2007-10-03 13:35:27 · 4 answers · asked by sdsurfachik 1

A block of mass 2.50 kg is pushed 2.80 m along a frictionless horizontal table by a constant 18.0 N force directed 25.0° below the horizontal.
(a) Determine the work done by the applied force.
J
(b) Determine the work done by the normal force exerted by the table.
J
(c) Determine the work done by the force of gravity.
J
(d) Determine the work done by the net force on the block.
J

2007-10-03 13:25:21 · 1 answers · asked by BMac 3

Two resistances, R1 and R2, are connected in series across a 9 V battery. The current increases by 0.100 A when R2 is removed, leaving R1 connected across the battery. However, the current increases by just 0.050 A when R1 is removed, leaving R2 connected across the battery. What are the two resistances?

2007-10-03 13:23:53 · 3 answers · asked by Hera08 1