ek 1001 -190

[inaccensa]

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Which of the following will change the acceleration of object m, if it were released from the top of the ramp?
yes, increase theta and the sin of the angle increases
The explanation is " net forceis proportional to mass and so acceleration is independent of mass." ??? huh

 

[geeyouknit]

Which of the following will change the acceleration of object m, if it were released from the top of the ramp?
yes, increase theta and the sin of the angle increases
The explanation is " net forceis proportional to mass and so acceleration is independent of mass." ??? huh

Can you post the full question?

 

[inaccensa]

Which of the following would change the acceleration of an object m if it were released from the top to bottom?
changing the shape
changing the mass
changing the angle
releasing the object from the middle of the ramp


Answer acceleration is given by a=gsintheta. because there is no friction. the shape of the object is irrelevant. The net force is proportional to the mass, so the acceleration is independent of the mass.

Never mind, I think they mean that the acceleration is constant and the force depends only on the mass of the object. Another q comes to mind, how does the shape of an object on an incline affect the friction. Is this same as air resistance, whereby increasing the surface area, increases the frictional force? How about a square block vs a sphere? Would the block experience more friction?

I know that a is independent of mass, but their explanation alludes me

 

[justhanging]

Which of the following would change the acceleration of an object m if it were released from the top to bottom?
changing the shape
changing the mass
changing the angle
releasing the object from the middle of the ramp


Answer acceleration is given by a=gsintheta. because there is no friction. the shape of the object is irrelevant. The net force is proportional to the mass, so the acceleration is independent of the mass.

Never mind, I think they mean that the acceleration is constant and the force depends only on the mass of the object. Another q comes to mind, how does the shape of an object on an incline affect the friction. Is this same as air resistance, whereby increasing the surface area, increases the frictional force? How about a square block vs a sphere? Would the block experience more friction?

I know that a is independent of mass, but their explanation alludes me

There suming all the forces in the x direction down the ramp and setting it equal to ma. Since there is no friction you just have to find the component of gravity that points down the ramp and since there is a net force you set that equal to ma.

mgSin(thetha) = ma

gsin(thetha) = a

The shape would matter if there is friction because some objects would spin at different rates if at all. Objects that spin would go faster down the ramp.

 

[inaccensa]

There suming all the forces in the x direction down the ramp and setting it equal to ma. Since there is no friction you just have to find the component of gravity that points down the ramp and since there is a net force you set that equal to ma.

mgSin(thetha) = ma

gsin(thetha) = a

The shape would matter if there is friction because some objects would spin at different rates if at all. Objects that spin would go faster down the ramp.

One of the other q's states that the material of the block and the incline determines the friction
Which of the following properties affects the coefficient of static friction between a block and an inclined plane?
gravity
mass of block
amount of surfacearea of the block making contact with the incline
the material of the block and plane---> correct ans.

I thought like airresistance the surfacearea will be detrimental to the frictional force, but thats not the correct ans. 😕

 

[Xivilus1231]

One of the other q's states that the material of the block and the incline determines the friction
Which of the following properties affects the coefficient of static friction between a block and an inclined plane?
gravity
mass of block
amount of surfacearea of the block making contact with the incline
the material of the block and plane---> correct ans.

I thought like airresistance the surfacearea will be detrimental to the frictional force, but thats not the correct ans. 😕

Frictional force is the (coefficient of friction of the object) times (how the object reacts to another object it is sitting on when opposing gravity, which is the normal force)

Usually these types of questions ignore air resistance (unless the topic is specifically about air resistance).

As strange is it may seem, surface area does not impact friction due to weight distribution. For example if you place a book flat, there is more atoms to distribute the mass of the book, if you lay it by the spine, there is less atoms so they impart more force.

The point is that increasing the surface area only serve to spread out frictional force, not increase it.

Look at it this way, if reducing surface area really reduce friction, then roller-blades would not be necessary since you can use ice skates to slide around concrete or asphalt.

 

[inaccensa]

👍 thanks🙂

Frictional force is the (coefficient of friction of the object) times (how the object reacts to another object it is sitting on when opposing gravity, which is the normal force)

Usually these types of questions ignore air resistance (unless the topic is specifically about air resistance).

As strange is it may seem, surface area does not impact friction due to weight distribution. For example if you place a book flat, there is more atoms to distribute the mass of the book, if you lay it by the spine, there is less atoms so they impart more force.

The point is that increasing the surface area only serve to spread out frictional force, not increase it.

Look at it this way, if reducing surface area really reduce friction, then roller-blades would not be necessary since you can use ice skates to slide around concrete or asphalt.