Physics - December 2007

A 500g hockey puck experiences an applied horizontal force of 50N [W] as it slides across the ice with an acceleration of 2.3 m/s2 [W] against the force of friction. Determine the magnitude and direction of the frictional force acting on the hockey puck.

2007-12-04 17:44:33 · 1 answers · asked by myname_isalbert 1

6. Two spacecraft in outer space attract each other with a force of 20 N. What would the attractive force be if they were one-half as apart?



8. The gravitational force between two very large metal spheres in outer space is 50 N. How large would this force be if the mass of each sphere were cut in half?




10. How does the Earth’s gravitational force on you differ when you are standing on Earth and when you are riding in a space shuttle 400 km above Earth’s surface? Earth’s radius is 6400 km.




16. The acceleration due to gravity on Titan, Saturn’s largest moon, is about 1.4 m/s/s. What would a 50-kg scientific instrument weigh on Titan?



22. By what factor is Earth’s gravitational field reduced at a distance of 5 Earth radii from the center of the Earth?

2007-12-04 17:19:31 · 1 answers · asked by Danielle P 1

1) A 2.00 x 10^3 kg car rounds a circular term of radius 20.0 m. If the road is flat and the coefficient of static friction between the tires and the road is 0.70, how fast can the car go without skidding?


2) A wooden bucket filled with water has a mass of 75 kg and is attached to a rope that is wound around a cylinder with a radius of 0.075 m. A crank with a turning radius of 0.25 m is attached to the end of the cylinder. What minimum force directed perpendicularly to the crank handle is required to raise the bucket?


Answer both or one of the questions. Any help you can give would be greatly appreciated! I really can't get these two. >.<

2007-12-04 17:11:28 · 1 answers · asked by Bernardita 2

(R=0.082 L atm/mol K, one mole of water has a mass of 1 grams)

2007-12-04 16:28:42 · 2 answers · asked by Anonymous

2007-12-04 15:41:54 · 3 answers · asked by Allison 1

I can hear electricity running through objects like tvs and computers. What is the hertz that electricity runs at? I would like to know. If anyone has this same ability, are there anyways for me to block the sound and not have it hurt as much?

2007-12-04 15:41:46 · 4 answers · asked by pippenintheshire 2

2007-12-04 15:32:41 · 22 answers · asked by my dinosaur life 3

An accident involves a car of mass 1964 kg which approachs a stationary car of mass 1020 kg. The driver of car A applies his brakes 12.3 meters before he crashes into car B. After the collision, car A slides 12.3 meters while car B slides 31.2 meters. The coefficient of kinetic friction between the locked wheels and the road for both cars is 0.630.

How fast was the driver of car A going before he hit the brakes?

I know this is a conservation of energy problem but it has friction involved so I dont know how to appoach the problem

2007-12-04 14:56:02 · 1 answers · asked by nameless 1

A 200,000kg DC-10 aircraft uses a run of 3.6km to achieve its takeoff speed 320km/h. If each of the three engines produces the same thrust and the acceleration is uniform, find the net thrust per engine. thxs again

2007-12-04 14:37:00 · 1 answers · asked by sascot 1

Is the momentum of a system always conserved? Explain by giving examples, please?

2007-12-04 14:34:46 · 3 answers · asked by Lisa R 2

Why do infrared satellites have to be cooled?

2007-12-04 14:32:44 · 4 answers · asked by Star_Gazer 1

Using a good digital watch, get the exact time when a bright star goes behind a distant building or tower. A day later time the disappearance again. Sighting over a nail fixed in a window sash will help you return your eye to the same location for each sighting. It will be found that:

a) the star disappears at the same time each night
b) the star disappears a little earlier each night
c) the star disappears a little later each night.

2007-12-04 14:27:31 · 1 answers · asked by ? 6

An 865 kg airplane starts at rest on an airport runway at sea level.
(a) What is the change in mechanical energy of the airplane if it climbs to a cruising altitude of 2400 m and maintains a constant speed of 95.0 m/s?
(b) What cruising speed would the plane need at this altitude if its increase in kinetic energy is equal to its increase in potential energy?

2007-12-04 14:14:58 · 3 answers · asked by p0oh 1

A 2g bullet is uniformly accelerated in a rifle barrel 1.2m long. If the bullet leaves the barrel with a speed of 300m/s, find the net force acting on the bullet in the barrel.

2007-12-04 14:11:09 · 1 answers · asked by sascot 1

A silver bar of length 30 cm and cross sectional area 1.0 cm^2 is used to transfer heat from a 100 degrees C reservoir to a 0 degree C block of ice. How much ice is melted per second? (For silver, k = 427 (SI units). For ice, Lf = 334 000 J/kg.)

2007-12-04 13:48:30 · 1 answers · asked by Mark N 1

13. You throw a tennis ball of radius R on the floor such that it rolls freely on a flat surface
for some time and then it hits a patch of ice where the coefficient of friction between the
ball and the ice is s = 0. When the ball hits the patch

(a) It continues to roll as before.
(b) It starts to spin
(c) It begins to skid
(d) none of the above

I think the answer is c) is it correct or do you think otherwise. please provide a short explanation with your answer.

2007-12-04 13:42:05 · 1 answers · asked by tellme 2

i want to do something original but not tooo hard. i have about a month to do it. its graded on how loud it plays, quality and difficulty of construction, it needs at least six notes, and i have to play a song with it. it cant have any prefabricated items, except guitar strings, but i dont want to make a guitar. i was thinking about doing the FUN song from spongebob but idk how many notes are in it....any ideas are welcome!!!!! thanx!! :)

2007-12-04 13:34:23 · 5 answers · asked by cottoncandy55 6

an exotic finish to massive stars is that a neutron star, which might have as much as five times the mass of our Sun packed into a sphere about 10 km in radius! Estimate the surface gravity on this monster.

answer: 6.7 x 10^12 m/s^2

is this one similar as the above in terms of solving it?

2. A typical white dwarf star, which once was an average star like our Sun but is now in the last stage of its evolution, is the size of our Moon but has the mass of our Sun. What is the surface gravity on this star?

answer 4.4 x 10^7 m/s^2

2007-12-04 13:28:19 · 1 answers · asked by Anonymous

2007-12-04 13:20:54 · 2 answers · asked by Everyone 4

ice water remain at 0 deg C? ( the answer is not .148 grams)

2007-12-04 13:15:20 · 1 answers · asked by Anonymous

I have a test on Friday and I need to get this question clearly awnsered. What is the difference between force and energy. My teacher said Energy- Ability to do work ; Force- Push or pull on an object. What is the difference. And also I'd appreciate a better explanation of Energy.

2007-12-04 13:11:58 · 2 answers · asked by Mustafa H 1

1. A certain dam is holding back fresh water 209 m deep. What is the water pressure at the base of the dam?

2.}
A 0.90 kg mass attached to a vertical spring of force constant 139 N/m oscillates with a maximum speed of 0.33 m/s. Find the following quantities related to the motion of the mass.
(a) the period
(b) the amplitude
(c) the maximum magnitude of the acceleration


3.}A bunch of grapes is placed in a spring scale at a supermarket. The grapes oscillate up and down with a period of 0.37 s, and the spring in the scale has a force constant of 670 N/m.

(a) What is the mass of the grapes?
(b) What is the weight of the grapes?

2007-12-04 13:11:22 · 1 answers · asked by Anonymous

1} A person in a rocking chair completes 23 cycles in 38 s. What is the period and frequency of the rocking?

2} The position of a mass oscillating on a spring is given by x = (3.9 cm) cos [2t / (4.40 s)].

(a) What is the period of this motion?
(b) What is the first time the mass is at the position x = 0?

3.)A typical tidal wave (tsunami) can have a speed of 739 km/h and a wavelength of 305 km. What is the frequency of such a wave?

4.)In a pig-calling contest, a caller produces a sound with an intensity level of 110 dB. How many such callers would be required to reach the pain level of 120 dB?
Two musicians are comparing their clarinets. The first clarinet produces a tone that is known to be 509 Hz. When the two clarinets play together they produce 8 beats every 2.00 seconds. If the second clarinet produces a higher pitched tone than the first clarinet, what is the second clarinet's frequency? (Express your answer to the nearest hertz.)

6.)A 89 kg person sits on a 3.5 kg chair. Each leg of the chair makes contact with the floor in a circle that is 1.7 cm in diameter. Find the pressure exerted on the floor by each leg of the chair, assuming the weight is evenly distributed
5.)

2007-12-04 13:08:40 · 2 answers · asked by Anonymous

He walks straight north until he is directly northeast of the post; then -always in a straight line- he walks northwest until he is directly north of the post; then west until he is west of it; then southwest until he is west of it; and so on, in a kind of segmented spiral. when he is again due east of the post, how many rods is he from it? show a diagram with all work including the answer and give the formula, with d = distance from post in rods and n = number of segments walked.

2007-12-04 12:46:27 · 1 answers · asked by Anonymous

An airplane traveling at 201 m/s makes a turn. What is the smallest radius of the circular path (in km) that the pilot can make and keep the centripetal acceleration under 5 m/s^2?

2007-12-04 12:43:38 · 2 answers · asked by SICK MY DUCK! 1

Which state in the US has the greatest tangential speed as the Earth rotates around its axis? Why?

Thanks

2007-12-04 12:39:43 · 2 answers · asked by Danielle P 1

Two parallel plates are uncharged. Does the set of plates have a capacitance? Explain.

2007-12-04 12:38:50 · 1 answers · asked by Jade 3

I really needed help i dont have the time to stay after school and ask for help. I am really busy trying to work and take care of my family. I would really thank everyone for their time to help me solve this problem.

2007-12-04 12:38:18 · 1 answers · asked by curiousadult 6

I need help solving this question, and I would really appreciate it if you took the time to walk me through it.

A 100 N block is positioned on an incline that makes a 25° angle. The coefficient of kinetic friction between the block and the incline is 0.15. A force of 125 N is applied by pulling a rope at a right angle of 35° above the incline.

a) (It says to draw free body diagram, but I know that's annoying to do, so can you just label the weight, its components, the friction force, the tension, and its components?)

b) Determine the magnitude and direction of the acceleration of the block.

What I'm having trouble with is that I don't know if factors like the normal force are made the addition of the perpendicular component of gravity as well as the perpendicular applied force of the rope? Or is it difference between the 2, because the rope is being pulled up, sort of relieving the actual perpendicular force of the weight?

2007-12-04 12:33:09 · 2 answers · asked by Andrew 2

2007-12-04 12:31:14 · 2 answers · asked by Anonymous