Question

11. You want to calculate the displacement of an object thrown over a bridge. Using -10 m/s2 for acceleration due to gravity, what would be the total displacement of the object if it took 8 seconds before hitting the water?

Answer 1

Displacement is d  

Vf² = Vi² + 2 g d  

(-20²) = (+10²) + 2 (-9.8) d  

-19.6 d = 300  

d = -15.3 m  

negative means lower

time is t  

d = Vi t + 1/2 g t²

-15.3 = 10 t + (-4.9) t²

4.9 t² - 10 t -15.3 = 0  

t = 3.06 s