Physics - November 2007

The figure shows a bicycle wheel resting against a small step whose height is h = 0.140 m. The weight and radius of the wheel are W = 22.0 N and r = 0.390 m. A horizontal force F is applied to the axle of the wheel. As the magnitude of F increases, there comes a time when the wheel just begins to rise up and loses contact with the ground. What is the magnitude of the force when this happens?

2007-11-19 05:28:45 · 3 answers · asked by mjamen 1

the end of a copper wire of diameter 0.30mm and length 1.50m is fused to one end of a steel wire of the same diameter and 1.20m in length. The wire is then hung vertically by attaching the free copper end to a fixed point and attaching a small weight to the lower end of the steel wire. The attachments reduce the length of each wire by 20mm. A load weight of 30N is then hung from the lower end of thesteel wire. Calculate
a) the stress in each wire,
b) the strain in each wire given that the Youngs modulas for steel is 2.0*10(power11)Nm(power-2) and for copper is 1.3*10(power11)Nm(power-2)
c) the total extension of the two wires

2007-11-19 05:16:55 · 1 answers · asked by Anonymous

(a) What is the minimum speed, relative to the Sun, necessary for a spacecraft to escape the solar system if it starts at the Earth's orbit?
(b) Voyager 1 achieved a maximum speed of 125,000 km/h on its way to photograph Jupiter. Beyond what distance from the Sun is this speed sufficient to escape the solar system?

2007-11-19 05:07:07 · 2 answers · asked by thisguyneedshelp121 1

A satellite of the Earth has a mass of 104 kg and is at an altitude of 1.98 106 m. (Assume that U = 0 as r .)
(a) What is the potential energy of the satellite-Earth system?
(b) What is the magnitude of the gravitational force exerted by the Earth on the satellite?
(c) What force does the satellite exert on the Earth?

2007-11-19 05:06:08 · 2 answers · asked by thisguyneedshelp121 1

Show that on a roller coaster with a circular vertical loop, the difference in your apparent weight at the top of the loop and the bottom of the loop is 6 g's - that is, six times your weight. Ignore friction. Show also that as long as your speed is above the minimum needed, this answer doesn't depend on the size of the loop or how fast you got through it. Beginning height of the coaster is,h, and radius of loop is R.

2007-11-19 05:02:21 · 1 answers · asked by Jonathan Smith 1

How much heat is required to raise the body temperature of a 60-kg woman from 21.9°C to 57.3°C?

2007-11-19 05:01:18 · 2 answers · asked by Anonymous

if you see that sign, # , in a physics equation, what does it represent?

2007-11-19 04:56:05 · 2 answers · asked by Nick S 2

2007-11-19 04:20:08 · 9 answers · asked by Tzone 1

if you have 10.8 meters per second, how do you convert that to radians per second?

i know that it is 2.7 rad/s but i cant figure out how it was done

2007-11-19 04:04:14 · 5 answers · asked by Nick S 2

2007-11-19 04:03:10 · 1 answers · asked by Anonymous

A 8 kg block is pushed by an external force against a spring with spring constant 173 N/m until the spring is compressed by 2.1 m from its uncompressed length (x = 0). The block rests on a horizontal plane that has a coefficient of kinetic friction of 0.56. The acceleration of gravity is 9.8 m/s^2. Remember: The block is not attached to the spring.

After all the external forces are removed (so the compressed spring releases the mass) how far D along the plane will the block move before coming to a stop? Answer in units of m.

2007-11-19 03:45:23 · 2 answers · asked by grouchy187 2

i was reading up on time travel and this guy said we have 4 dimensions we have macroscopic control over i was just wondering which ones they were

2007-11-19 03:43:46 · 3 answers · asked by Anonymous

2007-11-19 03:27:43 · 5 answers · asked by hudi 1

1) Is there any proof that indicates that the sizes of objects actually change size as the objects travel at speeds approaching c (the speed of light)?

2) If an object would travel at a speed close to c, then slow to a stop, would the object retain its original size?

Please explain length-contraction, I don't understand it!

2007-11-19 03:21:20 · 5 answers · asked by Michael n 2

Atmospheric pressure on Venus is about 90 times that on Earth. A steel sphere with a bulk modulus of 165 GPa has a volume of 2.50 cm3 on Earth. If it were put in a pressure chamber and the pressure were increased to that of Venus (9.12 MPa), how would its volume change (cm3)?

2007-11-19 02:57:49 · 1 answers · asked by Anonymous

hanging 2.00-kg block begins to accelerate a 4.74-kg block on a horizontal surface. But a rope connected to the wall at 31.5 degrees brings the block to an equilibrium position. The coefficient of friction between the surface and the 4.74-kg block is 0.130.



(a) What is the minimum tension (in Newtons) in the angled rope that maintains this equilibrium condition?
N

2007-11-19 02:55:35 · 1 answers · asked by ags101 2

2007-11-19 02:52:16 · 13 answers · asked by Anonymous

2007-11-19 02:43:38 · 5 answers · asked by Anonymous

suppose you have some clothing, and water will not take it out. If you have available cyclopentane and methanol, which would you choose as the more promising solvent to try? and why?

2007-11-19 02:22:33 · 1 answers · asked by tuazonicvirus 1

But when i convert feet to inches using 4.9x12 it says that i'm 58.8 inches. I'm confused. Which one is correct?

2007-11-19 02:22:19 · 0 answers · asked by Anonymous

what are rectified voltage?

2007-11-19 02:13:18 · 2 answers · asked by sakura 1

from the current technology and the recent breakthrough in science , how much closer are we to having a car that have no contact with ground?

2007-11-19 01:56:40 · 5 answers · asked by karta s 2

The parallel axis theorem provides a useful way to calculate the moment of inertia I about an arbitrary axis. The theorem states that I = Icm + Mh2, where Icm is the moment of inertia of the object relative to an axis that passes through the center of mass and is parallel to the axis of interest, M is the total mass of the object, and h is the perpendicular distance between the two axes. Use this theorem and information to determine the moment of inertia (kg·m2) of a solid cylinder of mass M = 5.40 kg and radius R = 8.10 m relative to an axis that lies on the surface of the cylinder and is perpendicular to the circular ends.

2007-11-18 23:42:15 · 1 answers · asked by mjamen 1

This is for my science fair project, have no idea why that happened, but the balls at 0 consistently went the farthest. Any explanations?

2007-11-18 21:51:58 · 3 answers · asked by Anonymous

In the arrangement of the figure, a string, tied to a sinusoidal oscillator at P and running over a support at Q, is stretched by a block of mass m. The separation L between P and Q is 1.19 m, and the frequency f of the oscillator is fixed at 119 Hz. The amplitude of the motion at P is small enough for that point to be considered a node. A node also exists at Q. A standing wave appears when the mass of the hanging block is 286 g or 447 g, but not for any intermediate mass. What is the linear density μ of the string?

2007-11-18 21:47:33 · 1 answers · asked by Anonymous

2007-11-18 21:17:55 · 6 answers · asked by bravo 2

Could I stand on top of the water without sinking?

2007-11-18 19:24:09 · 15 answers · asked by Anonymous

Say I weigh 200 pounds.

2007-11-18 19:14:50 · 12 answers · asked by Anonymous

2007-11-18 18:42:14 · 3 answers · asked by -michelle- c 1

i've looked up in a few books but haven't exactly got the def. of momentum.if someone could just give me the right explanation it'd be very helpful to me.
thanks.

2007-11-18 18:27:27 · 7 answers · asked by Anonymous