A 2kg block is sliding up a surface inclined at an angle of 30° above the horizontal. The block has the speeds indicated in the figure when it passes points L and K. The distance between points L and K is 2m. Which of the following includes a correct claim about the interaction of the block and the surface with supporting evidence from the figure?

The surface is rough, because the work-energy theorem indicates the block should be traveling faster at point  K .

Explanation:

Correct. Using the work-energy theorem, the speed at point K would be U1+K1=U2+K2

0+1/2mv^21=mgh2+1/2mv^22

v2= square root v^21−2gh2

=square root (7ms)^2−(2)(10)(2m)(sin30)

v2=5.4ms.

Since the actual speed at point K is slower than this value, there must have been friction between the block and surface.

beta is electron from nucleus

something from nucleus has changed, but charge must be same for cons of charge