Physics work problem...?

Question

A 4 kg block slides down a frictionless incline making an angle of 28 degrees with the horizontal. The acceleration of gravity is 9.81 m/s2.
Find the work done by the gravitational force when the block slides 1.2 m along the incline (in Joules).
What is the total work done on the block (in Joules)?
What is the speed of the block after it has moved 1.2 m if it starts from rest (m/s)?
What is its speed after 1.2 m if it starts with an initial speed of 1.3 m/s (answer in m/s)?

Thanks. The solution to any or all of these questions would be extremely helpful.

Answer 1

1.) W = Fd
For something sliding down an incline, F = ma sin θ. The sin θ is used to find the vertical component of the incline.
F = 4 kg * 9.81 m/s^2 * sin 28 = 18.422 N
W = Fd = 18.422 N * 1.2 m = 22.106 J

2.) Use Torricelli's Equation: Vf^2 = Vi^2 + 2ad. Here, Vi = 0, so:
Vf^2 = 2ad = 2 * 9.81 m/s^2 * sin 28 * 1.2 m = 11.042 m^2/s^2
Vf = 3.323 m/s

3.) Again, use Torricelli's Equation: Vf^2 = Vi^2 + 2ad. Here, Vi = 1.3, so:
Vf^2 = Vi^2 + 2ad = 1.69 m^2/s^2 + 2 * 9.81 m/s^2 * sin 28 * 1.2 m = 12.743 m^2/s^2
Vf = 3.570 m/s