- #1

alexs2jennisha

- 14

- 0

Part A

How much work is done by the horizontal force FP = 150 N on the 18-kg block of the figure(Figure 1) when the force pushes the block 5.5m up along the 32∘ incline? Assuming a coefficient of friction μk = 0.14. [Hint: Work-energy involves net work done.]

for W

_{Fp}i got 700 J

Part B

How much work is done by the gravitational force on the block during this displacement?

for W

_{gr}i got -510J

Part C

How much work is done by the normal force?

for W

_{N}i got 0 J

Now the part that I am having trouble

Part D

What is the speed of the block (assume that it is zero initially) after this displacement?

To do this part I did

initially I used the equation W

_{net}= 0.5mv

^{2}, with W

_{net}= W

_{Fp}+ W

_{gr}+ W

_{N}so W

_{net}= 190

and i solved for v by v = sqrt(2W/m) and got 4.6 m/s

that answer is incorrect. After consulting with my professor she said to take friction into account but now I am not sure how to do so.

I know that the normal force is mgcosθ + Fpsinθ and then the work of friction is equal to μk*F

_{N}*d*cosθ

I tried that and ended up with the velocity = 6.1 m/s

is there something I am not seeing?