A 200 g block on a 50-cm-long string swings in a circle on a hori...

Question

A 200 g block on a 50-cm-long string swings in a circle on a horizontal, frictionless table at 75 rpm. (a) What is the speed of the block?

Accepted Answer

Welcome back, everybody. We are taking a look at a 75 centimeter long massless horizontal bar and it is connected at one end to an electric motor. So let me just also know Tate its length real quick. 75 centimeters is also 750.75 m. Now connected to this electric motor, it is going to rotate around that electric motor. And we are told that it rotates at a constant speed of revolutions per one minute. And we are also told that a ball is located on the end the other end of this bar. And we are tasked with finding what is the ball's velocity here. Well, velocity is just going to be given by the radius of rotation times the angular velocity we have our radius but is our angular velocity in the right units here. Instead of revolutions per minute, we're actually going to need radiance per second. So let's go ahead and convert here. We know in one revolution, Sorry, in one revolution there is two pi radiance and in one minute, we have 60 seconds. So we will be able to plug this in and see that we get our ingredients per second. So let's go ahead and plug that in as well as our radius. So we get that this is equal to 0.75 times 48 times two pi divided by 60. And when we plug this into our calculator, we get approximately 3.8 m per second corresponding to our final answer. Choice of c Thank you all so much for watching. Hope this video helped. We will see you all in the next one.

A 200 g block on a 50-cm-long string swings in a circle on a horizontal, frictionless table at 75 rpm. (a) What is the speed of the block?

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