Physics - November 2007

A circular disk of radius 2.0 m rotates, starting from rest with a constant angular acceleration of 20.0 rad/s². What is the tangential acceleration of a point on the edge of the disk at the instant that its angular speed is 1.0 rev/s?

Can anyone show me how this problem is done? I have a feeling I am making it far more complicated than it should be. Thanks to anyone who can help!

2007-11-11 23:42:08 · 1 answers · asked by doubtful 2

2007-11-11 23:18:56 · 2 answers · asked by Katniss 2

The launching mechanism of a toy gun consists of a spring of unknown spring constant, as shown in Figure P5.33a. If its spring is compressed a distance of 0.160 m and the gun fired vertically as shown, the gun can launch a 23.0 g projectile to a maximum height of 24.0 m above the starting point of the projectile.

(a) Neglecting all resistive forces, determine the spring constant.
N/m
(b) Neglecting all resistive forces, determine the speed of the projectile as it moves through the equilibrium position of the spring (where x = 0), as shown in Figure 5.33b.
m/s

2007-11-11 22:42:16 · 3 answers · asked by Anonymous

how does air friction change the motion of a ball or the velocity of a ball coming down a ramp which is attached to a counter top? please kindly be as detailed as possible when explaining this.

Thank you, any help will be greatly appreciated.

2007-11-11 18:48:40 · 3 answers · asked by jumba 1

A woman is 1.8 m tall and has a mass of 60 kg. She moves past an observer with the direction of the motion parallel to her height. The observer measures her relativistic momentum to have a magnitude of 2.0 1010 kg·m/s. What does the observer measure for her height? Help please??

2007-11-11 18:34:18 · 4 answers · asked by darkangel_0219 1

Is there anything which will travel faster than light, I know some say human thoughts, but anything else ?

2007-11-11 18:22:54 · 10 answers · asked by Sr K 2

1. How can I relate any of the three Newton's law to pressure, friction, fluid, air resistance or the freely falling object. (Give me an example of any of them)

2. What is the formula for each law? (I heard something like a=F/M)

PLEASE HELP !!! I REALLY NEED TO KnOW THIS !!!!

Thanks !!!

2007-11-11 18:17:42 · 2 answers · asked by Summer W 1

A free falling object in the last second has travelled five times the distance it has travelled in its first second. What is the height it is falling from?
Please help cant figure out how to do it!!!

2007-11-11 16:16:50 · 3 answers · asked by Anonymous

1. A 1550 kg car moving south at 12.2 m/s collides with a 2360 kg car moving north. The cars stick together and move as a unit after the collision at a velocity of 5.90 m/s to the north. Find the velocity of the 2360 kg car before the collision.

2. Two carts with masses of 4.92 kg and 2.56 kg move toward each other on a frictionless track with speeds of 5.43 m/s and 3.08 m/s respectively. The carts stick together after colliding head-on. Find the final speed.

2007-11-11 15:10:10 · 3 answers · asked by Anonymous

Two objects attract each other with a gravitational force of magnitude 0.99 10-8 N when separated by 19.4 cm. If the total mass of the objects is 5.10 kg, what is the mass of each?

2007-11-11 14:42:32 · 1 answers · asked by Anonymous

A 150 N sphere 0.20 m in radius rolls, without slipping 6.0 m down a ramp that is inclined at 34° with the horizontal. What is the angular speed of the sphere at the bottom of the hill if it starts from rest?
(rad/s)

2007-11-11 14:41:25 · 1 answers · asked by Anonymous

bone has a young's modulus of about 18E9 Pa. Under compression, it can withstand a stress of about 160E6 Pa before breaking. assume that a femur is .50 m long, and calculate the amount of compression this bone can withstand before breaking

2007-11-11 14:17:22 · 1 answers · asked by Ashley P 1

a 3.0 kg block starts from rest at the top of a 30 degree angle incline and accelerates uniformly down the incline, moving 2.00 m in 1.50s .

it asks for accelertation which i got and its= 1.78 m/s^2
asks for speed of block after it has slid a distance of 2.0 which i got and its = 2.67 m/s
it asks for frictional force on the block and coefficient of kinetic energy between the block and incline i cant get these two can some one help me PLEASE!!!!!!!!!!!

2007-11-11 13:57:00 · 1 answers · asked by Anonymous

I need help drawing particle pictures cause i have no clue how to draw them. I tested 5ml, 10ml, 20ml, and 30ml.
When 5ml the can crushes the most, when 30ml crushes the least. how do i draw this?

2007-11-11 13:45:21 · 1 answers · asked by Fun&Sweet 3

I worked these multiple times and I keep getting the wrong answer.
1. A place kicker must kick a football from a point 31m from the goal. As a result of the kick, the ball must clear the crossbar, which is 3.05m high. When kicked the ball leaves the ground with a speed of 21.0 m/s at an angle of 59degrees to the horizontal. A) To determine if the ball clears the crossbar, what is its height with respect to the crossbar when it reaches the plane of the crossbar? B) To determine if the ball approaches the crossbar while still rising or while falling, what is its vertical velocity at the cross bar?
2. A daredevil is shot out of a cannon at 49.1degrees to the horizontal with an initial speed of 25.6m/s. A net is positioned at a horizontal distance of 32.3m from the cannon from which the daredevil is shot. At what height above the cannon's mouth should the net be placed in order to catch the daredevil?

2007-11-11 13:06:10 · 1 answers · asked by 5.8caloriewater 2

An airplane pilot fell 350 m after jumping from an aircraft without his parachute opening. He landed in a snowbank, creating a crater 1.1 m deep, but survived with only minor injuries. Assuming the pilot's mass was 81 kg and his terminal velocity was 50 m/s. What is the work done on him by the air resistance as he fell?

2007-11-11 12:53:14 · 1 answers · asked by mkj 2

identify the names of the groups on the periodic table?

i dont get it.
someone please help me.
[=

2007-11-11 11:40:37 · 1 answers · asked by ? 4

2007-11-11 11:29:01 · 19 answers · asked by diamondfairy890 2

A baseball is hit at 30m/s at an angle of 53 degrees with the horizontal. Immediately an outfielder runs 4 m/s toward the infield and catches the ball at the same height it was ht.

What was the original distance between the batter and the outfielder?

2007-11-11 10:54:32 · 1 answers · asked by Anonymous

thank you

2007-11-11 10:20:36 · 1 answers · asked by jumba 1

A 146N force is used to pulled a 350N wood block at constant speed by a rope making an angle of 50 degree with the floor. Find the coefficient of sliding function.

2007-11-11 10:10:34 · 1 answers · asked by Anonymous

What is the acceleration of two falling sky divers (mass 103.0 kg including parachute) when the upward force of air resistance is equal to one-fourth of their weight?
= ___ (downward)



After popping open the parachute, the divers descend leisurely to the ground at constant speed. What now is the force of air resistance on the sky divers and their parachute?
=___N (upward)

2007-11-11 09:30:17 · 1 answers · asked by Jon R 1

17) what is the intensity of the electromagnetic radiation at a distance of 2.00 m from a 100 W isotropic source?


18) A light ray in air strikes a glass surface with an angle of incidence of 30 degrees. The angle of refraction in the glass is 20 degrees. What is the index of refraction of the glass?

please help and explain to me how to do these problems, I am having a hard time and I have a crappy book that doesn't help me at all!!! thanks

2007-11-11 09:23:01 · 1 answers · asked by Anonymous

Example: if you rub a comb in ur hair, the comb will always recieve the negative charges and the hair always gives them.

2007-11-11 08:11:55 · 1 answers · asked by Shadowstrike 3

Starting from rest, a 12-cm-diameter compact disk takes 3.0 s to reach its operating angular velocity of 2000 rpm. Assume that the angular acceleration is constant. The disk's moment of inertia is .

How many revolutions does it make before reaching full speed?

I found the alpha, which is 0.001745
Then I used one of the kinematics equations to find theta, and I converted the radians answer to rev, I got 0.00125 but it's the wrong answer.

Can you provide the answer and how you did it. Thanks

2007-11-11 07:57:54 · 3 answers · asked by dawance88 2

a 44 kg block is pushed along the ceiling with a constant applied force of 85.0 N that acts at an angle of 55.0degrees with the horizontal. The block accelerates to the right at 6.00m/s^2. Determine the coefficient of kinetic friction between the block and the ceiling

2007-11-11 07:49:36 · 1 answers · asked by Anonymous

If you are doing a physics problem - what is wrong with this misconception? Why do people think this?

2007-11-11 07:43:34 · 5 answers · asked by boy101 3

Light incident on a pair of slits produces an interference pattern on a screen 2.3 m from the slits. If the slit separation is 0.016 cm and the distance between the bright fringes in the pattern is 0.77 cm, what is the wavelength of the light?

Which equation do I use for this? Any help would be appreciated!! Thanks!

2007-11-11 07:40:38 · 1 answers · asked by Kelly 1

I have heard varying reports as to whether microwave ovens heat from the outside in or from the inside out.
I always understood that heating from the inside is a myth. (I have certainly found that if food is not heated for a sufficient length of time, the centre can be cold whilst the edges can be hot/bubbling. Scientific answers please, rather than just opinions. Thanks

2007-11-11 07:37:17 · 8 answers · asked by Lynne R6 3

I think it does have something to do with the atomic structure, but to tell you the truth, I could not find the answer anywhere. physics Lecturers, come out and help!

2007-11-11 07:37:16 · 4 answers · asked by emrajbari 1