Physics - October 2007

okay, i have a block on a ramp 34 degrees above the horizontal, of mass 20kg. the ramp and block have a kinetic friction coefficient of 0.44.
the block initially has a velocity of 4.6ms-1 up the ramp.

i need to work out the work done on the block as it slides up to its highest point on the ramp.
i can say that the velocity at its highest point is 0 ms-1.

i have got a diagram drawn of the block on the ramp
mg drawn straight down from the block
mg sin x drawn down the slope
mg cos x drawn at a right angle to the slope

so apart from friction, these would be all the forces i need to consider if the block was just released to slide down the slope.
BUT, it is moving up the slope with that initial velocity.

so could somebody show me how i would go about finding the net force here?
my thoughts are that i have to somehow find out how far the block reaches up the slope before it can go no further, but i dont know how to do this.

a little explanation please? thanks.

2007-10-22 04:15:34 · 2 answers · asked by fpa06mr 5

2007-10-22 03:57:18 · 5 answers · asked by Anonymous

I need the solution for 1 dimensional wave equation. Please note that, when you assume any constant for deriving the solution,the actual value of the constant must also be derived. I would be grateful if anyone helped me.

2007-10-22 03:00:42 · 3 answers · asked by mega_10raisedto6 1

i havent got the slightest idea how to answer this:

A smoke detector operates using alpha particles from a radioactive Am 241 source.
A typical detector contains 0.2 milligrams of Am 241. the detector can only function if the mass of Am 241 exceeds 0.15 milligrams. Assuming that the lifetime of Am 241 is 624 years, calculate the operational time of the detector.

also does this mean its halflife is 624 / 2 = 312 years?
i've never seen any question like this before

2007-10-22 02:33:31 · 5 answers · asked by fpa06mr 5

A ladder 5.7m long rests against a vertical wall at angle f 34*(degrees)02' with the vertical wall. How far is the foot of the ladder from the wall? If the distance of the foot of the ladder from the wall is reduced to half its original distance, at what angle should the ladder be inclined to the wall?

2007-10-22 00:49:38 · 3 answers · asked by Anonymous

2007-10-22 00:38:48 · 4 answers · asked by Anonymous

Hi. Is there a formula somewhere in physics (I'm guessing it would be quite basic) which shows the relationship between momentum (Mass x Velocity) and height. The reason I ask relates to a physicist named Robert Goddard. He did as follows:

" In 1915, as assistant professor at Clark University, Worcester, he began experiments on the efficiency of rockets. He bought some commercial rockets and measured their thrust using a ballistic pendulum, a heavy mass suspended by ropes, to which the rocket was attached. The rocket was fired, and the height to which the pendulum rose provided a measure of the total momentum (mass times velocity) imparted to it. Goddard also used an equivalent set-up, where the mass pushed against a spring, instead of being suspended."
http://www.phy6.org/stargaze/Sgoddard.htm

So, I basically want to know, whats the mathematical formula or relationship that he used.

Thanks

2007-10-22 00:35:39 · 1 answers · asked by Anonymous

The weight of the block is 80 N. The coefficient of static friction between the block and the vertical wall is .60. a) What minimum force is required to prevent the block from sliding down the wall? and b) What minimum force F is required to start the block moving up the wall?


|
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> |__|
/ |
/ 40.0 |
angle

Sorry if the picture doesn't make a lot of sense. It shows the block on the wall, and force being applied at an angle of 40 degrees.

2007-10-22 00:18:43 · 2 answers · asked by Lolly 2

Could the universe really be splitting everytime we do something? Is it really impossible? Should they teach this is university classes, or even high school classes? Or should Niels Bohr theory still be taught?

2007-10-21 22:38:35 · 4 answers · asked by Anonymous

2 parallel window panes ( Area=0.5m^2 and o.oo6m thick) Are seperated by 0.006m of air.The inside of the glass is 24C and the outside is 3C. How much heat will be lost by conduction per hour?

2007-10-21 22:06:09 · 1 answers · asked by RockNRollStar 1

A passenger is pulling on the strap of a 15.0kg suitcase with a force of 70.0N. The strap makes an angle of 35 degrees above the horizontal. A 37.8N friction force opposes the horizontal motion of the suitcase. Determine the acceleration of the suitcase.

I'm okay with most force questions, but I have no idea what to do with the angle.

2007-10-21 21:43:34 · 6 answers · asked by bezi_cat 6

A plane is moving due north, directly towards it destination. Its airspeed is 200 mph. A constant breeze is blowing from west to east at 20 mph. In which direction is the plane pointed.

The answer to this question is 5.7 degree W of N...but i dont know how to get that answer...can someone please explain...

2007-10-21 21:22:14 · 3 answers · asked by smilenhope 1

2007-10-21 20:54:16 · 10 answers · asked by usman z 1

2007-10-21 20:44:40 · 3 answers · asked by aryan e 1

if a charged +Q and -Q on the plates of a capacitor are constant,what happens to the potential difference between plates when the plates are moved closer together?

2007-10-21 20:10:57 · 2 answers · asked by wizard21 1

the height at which it is dropped must be equal to 2.7 times the radius of the loop... from where is this 2.7 derived?

2007-10-21 19:14:40 · 3 answers · asked by Robert 1

I asked this a minute ago (all answered instantly) but I'm reading a book on Feynman and I'll quote: Time delay had not been a feature of the original electromagnetic theory. In Maxwell's time, on the eve of relativity, it still seemed natural to assume, as Newton had, that forces acted instantaneously. An imaginative leap was needed to see that the earth swerves in its orbit not because the sun is there but because it was there eight minutes before, the time needed for gravity's influence to cross nearly a hundred million miles of space--to see that if the sun were plucked away, the earth would continue to orbit for eight minutes.
From Genius ~ Richard Feynman and Modern Physics.
The text is from the 1940's. Is this relativity? Is it the current theory?

2007-10-21 19:05:07 · 9 answers · asked by Anonymous

2007-10-21 17:32:50 · 4 answers · asked by Anonymous

I was just reading an article from howstuffworks about parallel worlds and it seems very plausible but you don't hear a lot about the theory

2007-10-21 16:55:39 · 7 answers · asked by the_general64 1

At what angle should the gun be aimed so the target will be hit?

2007-10-21 16:40:41 · 2 answers · asked by TiTi 1

If this speed were increased by just 5.0 percent, how much longer would the jump be?

2007-10-21 16:39:08 · 1 answers · asked by TiTi 1

There are two blocks connected by a sting and tied to a wall. The mass of the lower block is 1 kg; the mass of the upper block is 2 kg. Given that the angle of the incline is 31 degrees, find the tension in (a) the string connecting the two blocks and (b) the string that is tied to the wall.

2007-10-21 16:10:49 · 2 answers · asked by mmeee 1

A hollow ball is rolling along a horizontal surface at 3.7 m/s when it encounters an upward incline. If it rolls without slipping up the incline, what maximum height will it reach?

2007-10-21 16:01:13 · 2 answers · asked by Anonymous

Here's an advanced-level question: An often recounted tale tells of the physicist who hid a large spinning flywheel inside his suitcase. The hotel porter took the suitcase and proceeded to walk around a corner to the left. What happens to the suitcase?

a) The suitcase simply pivoted around the corner in the way the porter wanted it to go, with the front of the case pivoting left and the back of the case pivoting right.

b) The case tended to pivot in a way exactly opposite to the way the porter wanted it to go, with the front of the case pivoting right and the back of the case pivoting left.

c) As the porter went around the corner the case pivoted top over bottom, with the top of the case pivoting left and the bottom of the case pivoting right.

d) As the porter went around the corner the case pivoted top over bottom, with the top of the case pivoting right and the bottom of the case pivoting left.

2007-10-21 15:40:09 · 2 answers · asked by ? 6

2007-10-21 15:35:36 · 3 answers · asked by Tland 3

A uniform door weighs 51.0 N and is 1.0 m wide and 2.5 m high. What is the magnitude of the torque due to the door's own weight about a horizontal axis perpendicular to the door and passing through a corner?

so far i've done: Ux=(51*1)/(2*25) =10.2N
Newtons 3rd Law=Dx=10.2N and Dy=51N
51N/10.2N =5 Nm but that's wrong. Anyone care to show me how to do this problem? Thanks!

2007-10-21 15:01:19 · 2 answers · asked by Anonymous

i need help. can anyone help me????

10. A 3.20 102 kg piano is being lifted at a steady speed from ground level straight up to an apartment 10.0 m above the ground. The crane that is doing the lifting produces a steady power of 4.00 102 W. How much time does it take to lift the piano?

12. A 50 g ball is thrown from a window with an initial velocity of 6.0 m/s at an angle of 30° above the horizontal.
(a) Using energy methods, determine the kinetic energy of the ball at the top of its flight.
(b) Determine its speed when it is 3.0 m below the window.

2007-10-21 14:52:44 · 1 answers · asked by flippin sweet 2

Given the situation in the figure below. The mass m1 is 0.64 kg and it is located at x1 = 30 cm. The pivot point is represented by the solid triangle located at x = 45 cm. The mass of the meter stick (mms = 0.40 kg) is located at its geometric center, xms = 50 cm. The mass m2 is 0.25 kg and it is located at x2 = 80 cm. Calculate the net torque (in N⋅m with the proper sign) due to these three weights. Use g = 9.8 m/s2.

There is a picture of a ruler with weights hanging at the locations listed above.

2007-10-21 14:44:11 · 1 answers · asked by Anonymous

Will a vector at 45 degrees to the horizontal be larger or smaller than its horizontal and vertical components ? By how much ? Explain why please !

2007-10-21 14:43:21 · 2 answers · asked by missybitsy 1

A 3000 kg car is parked at the top of a 6.9 m long driveway that is sloped at 16 degrees with the horizontal. The parking brake fails. If an average friction force of 4100 N impedes the motion, find the speed of the car at the bottom of the driveway. The acceleration of gravity is 9.8 m/s^2. Answer in units of m/s.

2007-10-21 14:28:27 · 1 answers · asked by PhysicsDumbass 1