As in Problem A above, a block of mass M starts from rest and is pushed up a frictionless ramp inclined at an angle θ above the horizontal by a constant force F. Use the work-energy theorem to find the block’s speed after it has been pushed a distance L up the incline. Your answer should be written in terms of M, θ, F, L and the acceleration due to gravity, g.

Respuesta :

Answer:

A(i)

The solution to this question is shown on the second uploaded image

A(ii)

The final speed is [tex]v = \sqrt{2L (\frac{F}{M} - gsin\theta )}[/tex]

B

The block speed after a distance L  is  [tex]v= \sqrt{2L (\frac{F}{M} -gsin \theta )}[/tex]

Explanation:

From the question  

The net force i the x-direction is mathematically represented as

               [tex]F_{net} = Ma[/tex]

From the the diagram in the second uploaded image we see that

             [tex]F_{net} = F - Mgsin \theta[/tex]

Therefore

              [tex]F- Mgsin\theta = Ma[/tex]

Making a the subject

              [tex]a = \frac{F}{M} - gsin\theta[/tex]

Applying the law of motion

                [tex]v^2 =u^2 + 2as[/tex]

where  u = 0 m/s and s =L

       [tex]v^2 = 0 + 2(\frac{F}{M} - gsin \theta )L[/tex]

=>   [tex]v = \sqrt{2L (\frac{F}{M} - gsin\theta )}[/tex]

According to Energy conservation law and work theorem

           Workdone by F + Workdone by gravity = change in kinetic energy

Mathematically this is given as

                [tex]F * L - (mgsin \theta)L = \frac{1}{2} M (v^2-u^2)[/tex]

   Since u = 0 m/s

                    [tex]L (\frac{F}{M} - gsin \theta ) = \frac{1}{2} v^2[/tex]

                  [tex]v= \sqrt{2L (\frac{F}{M} -gsin \theta )}[/tex]

Ver imagen okpalawalter8
Ver imagen okpalawalter8