Calculating Tangential & Angular Velocity of a Block on a String

  • Thread starter Thread starter akatsafa
  • Start date Start date
  • Tags Tags
    Circular
AI Thread Summary
To calculate the tangential and angular velocity of a block on a string, the correct approach involves first determining the angular velocity (ω) using the formula ω = (number of revolutions/time) × (2π). For a block making 15 rotations in 23.5 seconds, the angular velocity is calculated as approximately 4.01 rad/s. The tangential velocity (v) is then found by multiplying the radius (r) by the angular velocity, resulting in a value of about 2.807 m/s. The initial confusion arose from not accounting for the total number of revolutions in the calculations. Accurate application of these formulas yields the correct velocities.
akatsafa
Messages
42
Reaction score
0
I haven't worked with circular motions yet but i have these questions for lab. Could someone please help?

A group of students observes that a wooden block o mass o.29kg on a string makes 15 rotations in 23.5 seconds at a radius of 0.70 meters. (a) the blocks tangential velocity is.. (b) the blocks angular velocity is..

I tried using the equation v= 2pi r/T but that's not working. With that I got 0.87m/s but it's not right. What equations should I use for these?
 
Physics news on Phys.org
Hi, I think I got it but do check my work.

First we calculate the \omega and then we use it to find v.


\omega = \frac {15 \text{rev}}{23.5 \text{s}} \times \frac {2\pi}{1 \text{rev}} = 4.01 \text{rad/s}

Using v=r \omega we get v=2.807 \text{m/s}
 
Last edited:
thank you...that's right. I wasn't accounting for the 15 revolutions. I was just using one revolution.
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top