Jing S. answered 09/28/19
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- For the vertical direction, it's a constant acceleration g. For the javelin to fall back to the ground,
Sy = Vy t - 1/2gt**2 = 0, so Vy = 1/2 gt = 15m/s
- For the horizontal direction, it's a constant velocity. so
Sx = Vxt, so Vx = 45/3 15m/s.
- So the velocity of the javalin can be obtained by sqrt(Vx 2 + Vy2 ) = 21.21 m/s