How to calc velocity of a block sliding down

The velocity of a 1.3 kg block sliding down a frictionless inclined plane is found to be 1.49 m/s. 1.20 s later, it has a velocity of 4.49 m/s.

What is the angle of the plane with respect to the horizontal (in degrees)?

acceleration = g sin θ = (v - u) / t = (4.49 - 1.49) / 1.2 = 2.5

sin θ = 2.5 /9.8 => θ = 14.8 degree
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