Physics - September 2007

2007-09-19 18:00:36 · 5 answers · asked by Annette 1

2007-09-19 17:53:57 · 5 answers · asked by Annette 1

2007-09-19 17:39:25 · 1 answers · asked by aldo c 1

Two dogs pull horizontally on ropes attached to a post. The angle between the ropes is 51.0°. If dog A exerts a force of 310 N and dog B exerts a force of 230 N, find the magnitude of the resultant force and the angle it makes with dog A's rope.
____N
____°.

okay I know to find the angle i take the arctan of (Fy/Fx) but heres the problem for the magnitude I am having trouble figuring it out, I know to find magnitude I would take the square of the x values and the y values and square root it to find the magnittude but in finding these x and y values. do I take the giving forces and dived by cos(51) for x and sin(51) for y? I tried this and I tried multiplying yet I still could not get the proper answer. and of course the book does not properly explain this problem only problems that relate.

2007-09-19 17:15:01 · 2 answers · asked by Walachka 3

A soccer player kicks a rock horizontally off a 31.5 m high cliff into a pool of water. If the player hears the sound of the splash 3.6 s later, what was the initial speed given to the rock? Assume the speed of sound in air to be 343 m/s.
I don't get how to use the speed of sound...

The force exerted by the wind on the sails of a sailboat is 360 N north. The water exerts a force of 250 N east. If the boat (including its crew) has a mass of 270 kg, what are the magnitude and direction of its acceleration?

2007-09-19 17:14:19 · 1 answers · asked by christian8807 3

An experimental rocket plane lands and skids on a dry lake bed. If it's traveling at 83.0 m/s when it touches down, how far does it slide before coming to rest? Assume the coefficient of kinetic friction between the skids and the lake bed is 0.710.

2007-09-19 17:11:59 · 1 answers · asked by Anonymous

any simple answers are appreciated.

2007-09-19 17:09:55 · 3 answers · asked by Anonymous

Anyone?..

2007-09-19 17:07:38 · 4 answers · asked by Romina 3

2007-09-19 16:33:56 · 2 answers · asked by dyen2skate 1

An alpha particle with a Kinetic E of 7.00 MeV makes a head on collision with a gold nucleus at rest. What is the distance of closest approach of the 2 particles ( assume that the gold nucleus remains stationary and that it may be treated as a point charge. The atomic number of gold is 79, and an alpha particle is a helium nucleus consisting of 2 protons and 2 electrons. )

2007-09-19 16:32:54 · 1 answers · asked by sahar p 1

Why is a flame called "A Naked Flame"?

2007-09-19 16:27:25 · 4 answers · asked by Anonymous

If an electron is orbiting an atom, it can only exist in certain shells. Why can't an electron orbit an atom at any energy level, just like a moon could orbit a planet at pretty much any altitude? I welcome both short and long answers. I would especially appreciate links to diagrams or web sites that explain this well.

2007-09-19 16:26:58 · 4 answers · asked by Anonymous

by a horizontal force F.
What is the magnitude of F?

What is the magnitude of the force exerted by the ramp on the crate?

2007-09-19 16:25:05 · 1 answers · asked by tosinjesu 1

a tortoise can run with a speed of 16.0cm/s, and hare can run exactly 15 times as fast. In a race, they both start at the same time, but the hare stops to rest for 120 seconds. The tortoise wins by 20.0cm. How long does the race takes? What is the length of the race.

2007-09-19 16:22:39 · 1 answers · asked by Christina H 1

2007-09-19 16:21:01 · 8 answers · asked by dantedemitre 2

Emiy takes a trip, driving with a constant velocity of 89.5 km/h to the north except for a 22 min rest stop. If Emily's average velocity is 76.8 km/h to the north, how long does the trip take?

2007-09-19 16:19:46 · 1 answers · asked by Christina H 1

Four particles with masses 2kg, 7kg, 3kg, and 6kg are connected by rigid rods of negligible mass. The origin is centered on the mass in the lower right corner. The rectangle is 7m wide and 5 m long.

a) If the system rotates in the xy plane about the z axis with an angular speed of 6 rad/s calculate the moment of inertia of the system about the z axis. Answer in units of kgm^2.

b) Find the rotational energy of the system. Answer in units of J.

2007-09-19 16:15:10 · 1 answers · asked by Anonymous

I guess if you think about it, gravity has to be equally "distributed" (for lack of a better word), because the earth is round.
But then I've heard about these "Mystery spots" where they say there is no gravity or that the pull of gravity is not as strong.
Do these spots affect the earth in any way?
Could they possibly be placed there strategically (by God.. or for those who dont believe in god.. some "higher being" who created the earth) to keep the earth on track and rotating correctly?

2007-09-19 16:07:28 · 9 answers · asked by Anonymous

A rotating fan completes 1200 revolutions every minute. Consider the tip of a blade, at a radius of 0.15 m. Here are the questions: (a) Through what distance does the tip move in one revolution? Also, what are (b) the tip's speed and (c) the magnitude of it's acceleration? (d) What is the period of motion? Show and explain your work. Thanks!

2007-09-19 15:59:04 · 1 answers · asked by Anonymous

A small ball rolls horizontally off the edge of a tabletop
that is 1.20m high. It strikes the floor at a point 1.52m horizontally from the table edge. (a) How long is the ball in the air? (b) What is its speed at the instant it leaves the table? Show and explain your work. Thanks :)

2007-09-19 15:48:26 · 1 answers · asked by Anonymous

Science books tell us that the temprature of outerspace is something like 4 degrees Kelvin. How does one arrive at that conclusion? What is the temprature being measured from, or is it a theoretical temprature?

2007-09-19 15:40:25 · 2 answers · asked by bluecuriosity 2

Since gas expands in all directions, why, in a jet engine, does it create forward thrust, what keeps it from pushing air though the intake?

2007-09-19 15:37:24 · 2 answers · asked by gocougars1992 2

I have two questions regarding vectors. Can someone please help.

1)A person desires to reach a point that is 6.10 km from her present location and in a direction that is 35.0° north of east. However, she must travel along streets that are oriented either north-south or east-west. What is the minimum distance she could travel to reach her destination?

2)A car is driven east for a distance of 46 km, then north for 34 km, and then in a direction 26° east of north for 29 km. Draw the vector diagram and determine the total displacement of the car from its starting point.
find Magnitude

3) Vectors:
a = (5.0 m) i + (3.0 m) j
b = (-10 m) i + (3.0 m) j
What is the direction of a + b?


Find Direction ° (counterclockwise from east)

2007-09-19 15:23:22 · 1 answers · asked by illfolkuup 1

2007-09-19 15:13:59 · 11 answers · asked by jimmy 1

An electron of mass 9.11 10-31 kg has an initial speed of 5.00 105 m/s. It travels in a straight line, and its speed increases to 6.00 105 m/s in a distance of 9.00 cm.
(a) Assuming its acceleration is constant, determine the force exerted on the electron.
N (in the direction of motion)

if tried but i can't figure the time and if i get the time i can find the acceleration and the force,please help

2007-09-19 15:11:55 · 4 answers · asked by Dustin 1

A race car driver has a car that can accelerate at 5.9 m/s~2 (meters per second squared). He races against a souped-up stock car. Both start from rest, but the stock car leaves 1.0 seconds before sports car. The stock car moves with constant acceleration of 3.6 m/s~2 (meters per second squared).

1) Find time it takes for race car to overtake stock car
2) Find the distance that they go before they are side by side
3) Find velocity of both cars when they are side by side

2007-09-19 15:10:16 · 1 answers · asked by Rennix 2

A magnet produces a 0.30 T field between its poles, directed to the east. A dust particle with charge q = -8.0 10-18 C is moving straight down at 0.30 cm/s in this field. What is the magnitude and direction of the magnetic force on the dust particle?

2007-09-19 15:09:56 · 1 answers · asked by Anonymous

Why do you think it took so long?

2007-09-19 15:09:29 · 2 answers · asked by Moon O 1

A capacitor has a capacitance of 2.3*10-8F. In the charging process, electrons are removed from one plate and placed on the other plate. When the potential difference between the plates is 400V, how many electrons have been transferred?

2007-09-19 14:59:36 · 1 answers · asked by Anonymous

Find the minimum rate of change of f(x,y) = ln(x^2 + y^2) at the point (2, -3) and the direction in which it occurs.

2007-09-19 14:57:23 · 1 answers · asked by Anonymous