I like your lessons very much. Could you please tell me what is the acceleration in the first example (students, pushing on a car)? Are they pushing with a constant accelaeration of mu x mass x g in order to overcome friction? If force is defined as the product of mass and accelaration, are all sitituations,in which the instanteneous accelerations over some distance are changing, however the average acceleration over this distance is zero, examples of force? And what about work, when the average accelaration over distance is zero, however in small partitions the accelaration varies?
The cosine of theta is built into the equation. It does not matter which direction that you're pushing on the object. You always use the cosine function. The angle Theta is always the angle between the force and the direction the object is moving.
@@PhysicsclassroomVideos Its probably because as theta is between hypotenuse and base of right angle triangle i-e what came up in inclined plane physics, if we consider F as hypotenuse and displacement as base, then it makes sense to call angle between base and hypotenuse being cos theta.
Hi Mr. H, as usual, I was on the website studying first doing the "Check your understanding" then come here, I'm confused if W=Fxdxcos theta ; then why is it *W= (100N)(5m)(30 degrees) = 433 Joules?* I thought I should multiply the 3 factors.
@@PhysicsclassroomVideos okaaaay Cos 30 is √3/2 (0.86602540378) x 500 = *433* I'll find out how to get the value without using a calculator. Thanks! I love how your articles are mostly easy for me and funny too.
Dear Mr H, I have few points in my mind that I didn't get well..in definition of work related to waiter and tray example. If I accept it then it will tag work done by lifters , mechanical and manual lifting of objects as zero, because it will resemble the waiter carrying something.
Thanks for your reply but can't wrap my head around a point that a waiter carrying tray and moving a distance is no work but a person carrying books and covering a distance is work..any further help on how these analogies are different will be awesome.
In physics, "work" is when a force applied to an object moves the object in the same direction as the force. If someone pushes against a wall, no work is done on the wall because it does not move. However, depressing a letter on a computer keyboard requires work.
You are 1000 times better at explaining this than my physics professor
Thank you so much i have my finals in a week and thanks to your teaching I understood everything
Glad it helped!
Glad it helped!
Thank you so much, amazing lesson.
Fantastic! Thanks.
Nice and very informative video.
Thank u sir.
Your welcome.
I like your lessons very much. Could you please tell me what is the acceleration in the first example (students, pushing on a car)? Are they pushing with a constant accelaeration of mu x mass x g in order to overcome friction? If force is defined as the product of mass and accelaration, are all sitituations,in which the instanteneous accelerations over some distance are changing, however the average acceleration over this distance is zero, examples of force? And what about work, when the average accelaration over distance is zero, however in small partitions the accelaration varies?
Dear Mr H, if I lift something above the ground, as i am lifting vertically, why it's still be Fxd cos theta, why not sin theta.
The cosine of theta is built into the equation. It does not matter which direction that you're pushing on the object. You always use the cosine function. The angle Theta is always the angle between the force and the direction the object is moving.
@@PhysicsclassroomVideos Its probably because as theta is between hypotenuse and base of right angle triangle i-e what came up in inclined plane physics, if we consider F as hypotenuse and displacement as base, then it makes sense to call angle between base and hypotenuse being cos theta.
Hi Mr. H, as usual, I was on the website studying first doing the "Check your understanding" then come here, I'm confused if W=Fxdxcos theta ; then why is it *W= (100N)(5m)(30 degrees) = 433 Joules?* I thought I should multiply the 3 factors.
Should be *cos(30°). Try that.
@@PhysicsclassroomVideos okaaaay Cos 30 is √3/2 (0.86602540378) x 500 = *433* I'll find out how to get the value without using a calculator. Thanks! I love how your articles are mostly easy for me and funny too.
Dear Mr H,
I have few points in my mind that I didn't get well..in definition of work related to waiter and tray example. If I accept it then it will tag work done by lifters , mechanical and manual lifting of objects as zero, because it will resemble the waiter carrying something.
Nope. Lifting involves work because the force is in the direction that the object moves. The angle is 0ﾟ.
Thanks for your reply but can't wrap my head around a point that a waiter carrying tray and moving a distance is no work but a person carrying books and covering a distance is work..any further help on how these analogies are different will be awesome.
perfect
In physics, "work" is when a force applied to an object moves the object in the same direction as the force. If someone pushes against a wall, no work is done on the wall because it does not move. However, depressing a letter on a computer keyboard requires work.
Yes. Work is done on the key.
when thete is 120 degree