A mistake in a physics SAT prep book or an Underlying Paradox in freefall explanation?! HELP NEEDED

TechieCSG
Sat, 09 Aug 2014 12:54:40 +0000

For the first problem you can use vf = vi + at; here as the ball reaches its max height vf = 0, so you get vi = -at. ‘a’ here is acceleration and t is time so you get the value of vi as 9.8*1.8 = 17.64

For the 2nd problem, you can divide the velocity into 2 components, vertical and horizontal component.
The vertical component is equal to vsin(30) = 11. So if you just consider the vertical component of the velocity the problem becomes like a free fall problem. Using this, find the time of flight of the lure which is ~1.12 seconds. Now, consider the horizontal component of the velocity. The distance covered would be s = ut + 0.5a(t^2), but acceleration in the horizontal direction is zero, so distance = vcos(30) * 1.12 = ~ 21.388