Calculate the hang time of an athlete who jumps a vertical distance of 0.75 meter

The time it takes going up will be equal the time returning: 
s = s0 + v0t + (1/2)at^2 
Taking the top of the jump as 0 and positive direction downward, 
h = 0 + 0 + (1/2)gt^2 
t = √(2h/g) 
Since the hang time will be twice the time to rise or fall, therefore:

T = 2t
T = 2√(2*0.75/9.80665) 
T ≈ 0.78 seconds

convex lenses are thicker at the middle. rays of light that pass through the lens are brought closer together (they converge). a convex lens is a converging lens. when parallel rays of light pass through a convex lens the refracted rays converge at one point called the principal focus.

i had this question and the answer was 3.15 miles.

martina travels from school to her mom's office. from there, she walks to school. after school, she walks to the library and then to a friends house before finally ending back at home. find martina's total distance traveled.

a) 0 miles  

b) 0.4 miles  

c) 1 mile  

d) 3.15 miles