# Search results

1. ### Average angular speed

I think I found it in the textbook: Since the angular acceleration is constant: Avg ang velocity= 1/2[wo + w] = 1/2[8+10]= 9 rad/s
2. ### Average angular speed

This is where I get confused with Physics. Are speed and velocity the same thing? Redoing the math, which I hope is right: Avg speed is (10 rad/s + 8 rad/s) / 4 s = 4.5 rad/s Vt = r*w = 4 m * 4.5 rad/s = 18 rad/s Or do I not need to go as far to find Vt?
3. ### Average angular speed

Homework Statement A grindstone of radius 4.0m is initialy spinning with an angular speed of 8.0 rad/s. The angular speed is the increased to 10rad/s over the next 4.0 seconds. Assume that the angular acceleration is constant. What is the average angular speed of the grindstone? Homework...
4. ### Excel spreedsheet for Range formula- Lab

I have to program the range formula R= [Vo2sin(2*theta)]/g, into an Excel spredsheet. I need to progran the equation for various values of 'theta' to determine for which value(s) of 'thet' is the range maximum. Table should have left side Injection angle (degrees), right side Range (R). The...
5. ### Volume (Math check)

OK, think I got it now: V= m/p Air = 15.76 / 8470 = 1.8 x 10^-3 Water = 13.86 / 8470 = 1.6x10^-3 Difference of the two is 2x10^-4, which happens to be one of the answers.
6. ### Volume (Math check)

What I did is find the volume of the brass in the air, then the volume in the water and found the difference between the two. This is not the correct answer though. What did I do wrong?
7. ### Volume (Math check)

A small sculpture made of brass (p = 8470 kg/m^3) is believed to have a secret central cavity. The weight of teh sculpture in air is 15.76N. When it is submerged in water, the weight is 13.86N. What is the volume of the secret compartment? Fb = W W = pgV 15.76 = 8470 * 9.8 * V 15.76 =...
8. ### Pressure on incline

An ice cube, p = 917 kg/m^3, is sliding down a 16 degree frictionless incline. The sides of the cube each have a length of .75 m. What pressure does the cube exert on the incline? P = F / A = F / .75^3 = F / .42 F = ma = 917 * a I am having a problem figuring out the Force...
9. ### What is the total rotational kinetic energy of the wheels?

thanks. I knew I was forgetting something. It just didn't look right.
10. ### What is the total rotational kinetic energy of the wheels?

A 50kg rider on a moped of mass 75kg is traveling with a speed of 20 m/s. Each of the two wheels of the moped has a radius of 0.2m and a moment of inertia of 0.2 kg*m^2. What is the total rotational kinetic energy of teh wheels? KEr = 1/2Iw^2 = 1/2(.02)(20)^2 = 4 Two wheels = 2...
11. ### Spring Constant of ping-pong ball

The conservation of energy states that the total of all energies before the process is equal to the total energies after the process. Forgive me, but I am not understanding how to apply that to this problem. :(
12. ### Spring Constant of ping-pong ball

A ping-pong ball weighs 2.5x10^-2N. The ball is placed inside a cup that sits on top of a vertical spring. If the spring is compressed .055m and released, the maximum height above the compressed position that the ball reaches is 2.84m. Neglect air resistance and determine the spring constant...
13. ### Speed vs Velocity

Is there a difference between the two? The problem reads: A grindstone of radius 4.0m is initially spinning with an angular speed of 8 rad/s. The angular speed is then increased to 10 rad/s over the next 4 seconds. Assume that the angular acceleration is constant. What is the average angular...
14. ### Angular acceleration spin-dry cycle

Just checking to see fi I did the math right: During the spin-dry cycle of a wash, the motor slows down from 95 rad/s to 30 rad/s while turning the drum through an angle of 402 radians. What is the magnitude of the angular acceleration of the motor? = 1/2(Wo + W)t 402 = 1/2(95 +...

If I was given 477 rev/min and I need to convert to radians, I would use: 477rev (2*pi radians/1 rev) = 2997.07 radians Question is do I need to divide by 60 to get radians/second instead of minutes?
16. ### Average Net Force

WOW! I brain farted that one. For some reason I was thinking to replace the "a*t" with 27. Don't know why... Thank you for your help, I really appreciate it.
17. ### Average Net Force

Anyone have any info on this?
18. ### Average Net Force

So, using your equations I get: 120m = 1/2 (27m/s)^2 120m = 1/2 (729m^2/s^2) 120m = 364m^2/s^2 rearrange--> s^2 = 364m^2/120m s^2 = 3.03m This isn't right...
19. ### Height of tree Homework problem

I may be wrong, but: Opposite = adjacent * Tan angle = 76 * Tan 32 = 47.5 Is that one of your answers? If not, forget I replied. :D
20. ### How much work was done by the tension in the cable?

So F= 0 and T= mg?
21. ### Average Net Force

An 810-kg car accelerates from rest to 27m/s in a distance of 120m. What is the magnitude of the average net force acting on the car? 120m / 27m/s= 4.4 s F=ma =810kg * 4.4s = 3600 N This is not one of my choices. What did I do wrong?
22. ### How much work was done by the tension in the cable?

I think I have been staring at this question too long as I can not figure it out. I am sure the answer is simple: A 1500-kg elevator moves upward with a constant speed through a vertical distance of 25m. How much work was done by the tension in the cable? I know that W= (F cos 0)s, and...