Kinematics: Solving 2 Projectile Flight Time Diff.

[Kyoma]

I have trouble solving this question:

2 projectiles are launched with identical speeds of 30m/s and at angles 40 degrees and 50 degrees with the horizontal, respectively. The difference between the flight times of the 2 projectiles is?

The answer given to me is 0.754s, round up to 3 significent figures.

 

[AJ Bentley]

Just treat it as two separate projectile problems.

Velocity is 30m/s so for the first, resolve the velocity horizontally and vertically at an angle of 40 degrees.
You can then calculate the flight time using just the vertical velocity (v = u + at).

Do the same for the second and subtract the results.

 

[Delta2]

$$v_{y1}=30sin(40)=19.283, v_{y2}=30sin(50)=22.981$$

The flying times given that $$g=9.81m/s^2$$ are $$t_{1}=\frac{2v_{y1}}{g}=3.931,t_{2}=\frac{2v_{y2}}{g}=4.685$$