Physics - September 2007

i want to know exactly what interaction is there between the magnetic field of a conductor and the magnetic field of the magnet that makes the conductor to experience the Lorentz force when placed perpendicular to the magnetic feild and also why this force does'nt apply when the conductor is placed parallel to the magnetic field.

2007-09-10 02:37:39 · 4 answers · asked by Anonymous

A spherical ball is placed on a plane surface inclined
at θ to the horizontal. Determine the linear
acceleration of the center of the sphere down the
incline if:
1) θ = 40 degrees
2) θ = 50 degrees

Coefficient of static friction, μs = 0.3
Coefficient of kinetic friciton, μk = 0.2
Mass moment of inertia of a sphere, J = 2/5 m*R^2

2007-09-10 01:55:36 · 4 answers · asked by Dr D 7

why? why not?

2007-09-10 01:36:30 · 8 answers · asked by We don't fight fair. 1

that is like one dimension ,two dimension three dimension etc etc like wise in which dimension we are living?

2007-09-10 00:54:08 · 4 answers · asked by Anonymous

explain..

2007-09-10 00:38:34 · 5 answers · asked by We don't fight fair. 1

Question 5
Liyana made the following notes when she observed organisms A,B,C and D in a particular ecosystem:
A grows well only if it can find a spot on B. As A grows, B also grows. B and C will reproduce only if D is present. When B reproduces, A and will die. C feeds on D, and D feeds on B.

Which of the organisms, A, B, C or D, is the parasite in this ecosystem?

Pls submmit your answers by 6.30pm. Thank you for your help.

2007-09-09 23:25:49 · 2 answers · asked by danieltay93 3

You can spin the egg. Since viscosity is a measure of a liquid's resistance to shear forces, seeing how the egg resists spinning (or continues to spin after you stop it) will tell you something about its viscosity. A thin yolk will continue to spin after you stop it because the inner yolk continues to spin even though the outer layers are stopped. As the inner yolk spins, it applies a shear force to the outer layers, which eventually cause the egg to spin again. A very viscous yolk (say, a hard boiled egg) resists shearing altogether, and the inner yolk stops when you stop it, so there is no spinning afterwards.

2007-09-09 22:41:59 · 3 answers · asked by physics maniac 2

a regular tetrahedron is a three-dimensional object that has four faces, each of which is an equilateral triangle. Each of the edges of such an object has a length L. The height H of a regular tetrahedron is the perpendicular distance from one corner to the center of the opposite triangular face. Show that the ratio between H and L is H/L = sqrt 2/3.
Please help if you can. Answers only are great but they don't help come test time. Can anyone break this down in understndable terms?? All help is appreciated!! Thanks!

2007-09-09 22:12:08 · 2 answers · asked by Curt 2

A cart with mass 19.5 kg is intitally at rest. You get it moving by pushing on the cart at an angle of θ = 33.9° from above the horizontal. The magnitude of your force as a function of time is given by: Fyc(t) = Foe-b t, where b = 0.46 s-1 and Fo = 141.6 N. You can assume that the wheels on the cart are good enough that you can neglect friction between the cart and ground.
What is the speed of the cart when t = 4.7 s?

I know that i need to use newton's second law. I worked on it for hours, but can not get it. please help. Thank you so much.

2007-09-09 21:57:38 · 3 answers · asked by moonlightNY 1

A cart with mass 19.5 kg is intitally at rest. You get it moving by pushing on the cart at an angle of θ = 33.9° from above the horizontal. The magnitude of your force as a function of time is given by: Fyc(t) = Foe-b t, where b = 0.46 s-1 and Fo = 141.6 N. You can assume that the wheels on the cart are good enough that you can neglect friction between the cart and ground.
What is the speed of the cart when t = 4.7 s?

I know that i need to use newton's second law. I worked on it for hours, but can not get it. please help. Thank you so much.

2007-09-09 21:04:26 · 1 answers · asked by moonlightNY 1

A block is resting on a ramp. You can change the inclination angle (theta) by raising one end of the ramp. The block has a mass m = 9.5 kg. At the interface between the ramp and the block, the coefficient of static friction is ms = 0.45, and the coefficient of kinetic friction is mk = 0.315.
If you raise the end of the ramp very slowly so that you can assume a = 0 for the block, at what angle will it slip?

Also,If it slips at that angle, what will the magnitude of its acceleration be?

And, if you can, How long does it take from the time it slips to travel a distance d = 0.90 m down the ramp?

Thank you so much.

2007-09-09 20:14:02 · 3 answers · asked by moonlightNY 1

In my opinion we can see an object by the light reflecting from the object. But If the light is under the specises, I think, it passes through the object and we cannot see the light reflecting from the object. so we can't see the object but see just the light itself.

What's wrong in my thoughts?

2007-09-09 18:49:40 · 4 answers · asked by Anonymous

A major leaguer hits a baseball so that it leaves the bat at a speed of 28.5m/s and at an angle of 36.9 degrees above the horizontal. You can ignore air resistance.

At what two times is the baseball at a height of 9.50m above the point at which it left the bat?

2007-09-09 18:47:06 · 3 answers · asked by ! 2

2007-09-09 18:20:22 · 6 answers · asked by Lim S 3

A 4.04 kg block located on a horizontal floor is pulled by a cord that exerts a force F = 10.3 N at an angle q = 16.0° above the horizontal. The coefficient of kinetic friction between the block and the floor is 0.070. What is the speed of the block 3.70 s after it starts moving?
I know that static friction can be ignored. Any idea how to solve this? I worked on it for over an hour. Please help.
Thank you....

2007-09-09 18:13:17 · 3 answers · asked by moonlightNY 1

i know- i need to learn this on my own. i had a lot of other work and a teacher who i cant even understand, so if you could just help me out w/ any of these, it'd be great.....

A ranger in a national park is driving at 35 km/h when a deer jumps onto the road 50 m ahead of the vehicle. After a reaction time of t s, the ranger applies the brakes to produce an acceleration of -2.40 m/s2. What is the maximum reaction time allowed if the ranger is to avoid hitting the deer?

An elevator is moving upward at 1.01 m/s when it experiences an acceleration 0.32 m/s2 downward, over a distance of 0.84 m. What will its final velocity be?

A rocket moves upward, starting from rest with an acceleration of 27.0 m/s2 for 4.72 s. It runs out of fuel at the end of the 4.72 s but does not stop. How high does it rise above the ground?

2007-09-09 18:03:31 · 3 answers · asked by tar_heel_fan_44 2

How to solve the belowing question?
A solid sphere with a diameter of 0.17m is released from rest, it then rolls without slipping down a ramp, dropping through a vertical height of 0.61m. The ball leaves the bottom of the ramp, which is 1.22m above the floor, moving horizontally.
Through what horizontal distance(d) does the ball move before landing?
How many revolutions does the ball make during its fall?

2007-09-09 17:43:25 · 3 answers · asked by クリスマス ^-^ 2

A parachutist descending at a speed of 9.40 m/s loses a shoe at an altitude of 31.60 m.

(a) When does the shoe reach the ground?

(b) What is the velocity of the shoe just before it hits the ground?

2007-09-09 17:26:40 · 2 answers · asked by tar_heel_fan_44 2

In the classroom demonstration where a volunteer strikes an anvil resting on the physics professor's chest will he lies reclined, the anvil shields the daring physics professor from most of the sledgehammer's:

a) momentum
b) kinetic energy
c)...both
d)...actually neither

2007-09-09 17:20:58 · 1 answers · asked by ? 6

A golfer rides in a golf cart at a speed of 3.10 m/s for 30.0 s. She then gets out of the cart and starts walking at an average speed of 1.50 m/s. For how long (in seconds) must she walk if her average speed for the entire trip, riding and walking, is 2.50 m/s?

2007-09-09 17:17:53 · 1 answers · asked by puji831 1

A person looking out the window of a tall office building observes what he suspects is a UFO. The person records the position of the object as a function of time and finds it is given by *r*(t) = -(5.0 m/s)t*i*+ (10.0 m/s)t*j*+ [(7.0 m/s)t - (3.0 m/s2)t2]*k*

(a) Find the displacement, velocity, and acceleration vectors for the object at t = 2.0 s.
r(2s)= ____i +____ j +_____k
v(2s)=____i +____ j +_____k
a(2s)=____i +____ j +_____k

b) Is there a time when the object has a velocity of zero?


c) Is the acceleration of the object constant, or does it change with time?

2007-09-09 17:09:36 · 1 answers · asked by Walachka 3

A certain vector in the xy plane has a y component = 10 & x component = 4. The vector is rotated in the plane so that the x component is doubled. What is the new y component?

I don't get the concept of this question, can anyone provide an explanation to me? thanks

2007-09-09 16:40:10 · 2 answers · asked by superman 4

A golfer rides in a golf cart at a speed of 3.10 m/s for 30.0 s. She then gets out of the cart and starts walking at an average speed of 1.50 m/s. For how long (in seconds) must she walk if her average speed for the entire trip, riding and walking, is 2.50 m/s?

2007-09-09 16:37:07 · 1 answers · asked by puji831 1

As you eat your way through a bag of chocolate chip cookies, you observe that each cookie is a circular disk with a diameter of 8.50 +- 0.02 cm and a thickness of 0.050 +- 0.005 cm. Find the uncertainty of the ratio of the diameter to the thickness.

2007-09-09 16:22:49 · 1 answers · asked by Anonymous

A pulsar is receding directly away from the Earth with a speed of 8.0 C, a starship is sent towards the pulsar with a speed of 0.95 C relative to the earth. If an earth observer sees 153 pulses emitted every second, what rate does the starship see the pulses?

2007-09-09 16:14:55 · 2 answers · asked by Mike M 2

A particle has a constant acceleration of a = (6i + 4j) m/s^2. At time t =0, the velocity is zero and the position vector is r - (10m) i. Find the velocity and position vectors at any time, t.

2007-09-09 16:14:36 · 1 answers · asked by Anonymous

One car is going 88km/h and the other is going 115 km/h, suppose they are both going in the same direction with the same starting position. How far must the faster car travel to arrive 16 mins before the slower car? Answer in units of km.

2007-09-09 16:00:53 · 1 answers · asked by Skyler H 1

2007-09-09 16:00:43 · 4 answers · asked by dsgc05™ 6

...a regular light?

2007-09-09 15:51:50 · 5 answers · asked by slguthmuller 2

I know what the answer is, but I don't know how to get there!

Question: A ball is thrown upward from the ground w/ an initial speed of 25 m/s; at the same instant, another ball is dropped from a building 15 m high. After how long will the balls be at the same height?

Answer: 0.60 s

2007-09-09 15:46:27 · 4 answers · asked by smeiou78 4