Ahot-air balloon is drifting straight downward with a constant speed of 2.40 m/s. when the balloon is 7.63 m above the ground, the balloonist decides to drop one of the ballast sandbags to the ground below. how much time elapses before the sandbag hits the ground?

1.03 seconds

Explanation:

x = x₀ + v₀ t + ½ at²

0 = 7.63 + (-2.40) t + ½ (-9.8) t²

0 = 7.63 - 2.40 t - 4.9 t²

Solve with quadratic formula:

t = [ -b ± √(b² - 4ac) ] / 2a

t = [ 2.40 ± √(2.40² - 4(-4.9)(7.63)) ] / -9.8

t = -1.52, 1.03

Since t can't be negative here, the sandbag hits the ground after 1.03 seconds.

work: w = fd (given)

work done by chet   =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.

the simple machine has three main features. they are:

fulcrum is the center point or pivot point of the machine. effort is input force/ applied force. load is external force/ output.

the keisha 's machine labels are

x : load

y: fulcrum

z: lever