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**Problem with Kinetic Enery**

1) A 285-kg load is lifted vertically with an a = 1.060 g (1.57m/s^2), by a single cable. Determine (a) the tension in the cable (b) The net work done on the load (c) work done by the cable on the load (d) work done by gravity on the load (e) final speed of the load, assuming it started from rest.

I did a correctly gettng a tension of 3240 = 3.2 x 10^3 N

The rest I am clueless about. The quation for work (W=Fdcos) confuses me. Can anyone help me? (And yes I did draw a free-body diagram)

For part b I would say you add up all the works done by forces (T, Weight of object, and Normal force?

*Correct Answers for b-e: 9.83 x 10^3 J, 7.13 x10^3 J, -6.14 x 10^4 J, 8.31 m/s*

**Problem involving potential energy**

2) A 1200-kg car rolling on a horizontoal surface has speed v=65km/h when it strikes a horizontial coiled spring and is brought to rest in a distance of 2.2 m. What is the spring stiffness constant of the spring?

No idea at all how to attempt to find what the question is looking for. All I got was a conversion of v into m/s and then drew my free body picture.

*Correct answer: 8.1 x10^4 N/m*

**Problem with Conservation of Mechanical Energy**

3) A sled is intially given a shove up a frictionless 28 degree incline. It reaches a maximum vertical height 1.35 m higher than where it started. What was the intial speed?

My thoughts were to find the work done by sled in a vertical motion? Which would by F x d x cos angle. But there is no force given in the poblem or mass of the sled.

*Correct answer: 5.14 m/s m/s*

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