Superguy is flying at treetop level near Paris when he sees the Eiffel Tower elevator start to fall (the cable snapped). His x-ray vision tells him Lois LaTour is inside. If Superguy is 1.00 km away from the tower, and the elevator falls from a height of 122.5 m, how long does Superguy have to save Lois, and what must be his average speed?

Question

Superguy is flying at treetop level near Paris when he sees the Eiffel Tower elevator start to fall (the cable snapped). His x-ray vision tells him Lois LaTour is inside. If Superguy is 1.00 km away from the tower, and the elevator falls from a height of 122.5 m, how long does Superguy have to save Lois, and what must be his average speed?

A) 3.00 s, 333 m/s
B) 5.00 s, 200 m/s
C) 7.00 s, 143 m/s
D) 9.00 s, 111 m/s
E) 10.0 s, 96.0 m/s

Answer 1

H=1/2gt^2

t=sqrt(2h/g)
=sqrt(2*240/9.8)
=6.99sec

speed=d/t
=1000/7
=142.8m/s

Answer 2

Have you calculated how long it takes the elevator to free fall 122.5 m? That would be a good way to start.

Once you have calculated that time T, the speed required is easy: 1000m/T

One of the choices fits perfectly

Answer 3

I am really not good at physics. How would I go about finding how long it takes the elevator to fall?

Is it going to have something to do with 9.8m/s?

Answer 4

H = (1/2)g T^2, so

T = sqrt(2H/g) is the time to fall

yes, it has something to do with g.

People aren't "good at physics" until they try solving the problems.

Answer 5

To calculate the time Superguy has to save Lois and his average speed, we can use the concept of free fall.

First, let's calculate the time it takes for the elevator to fall from a height of 122.5 m. Using the equation for free fall:

d = 1/2 * g * t^2

where d is the distance, g is the acceleration due to gravity (approximately 9.8 m/s^2), and t is the time.

Rearranging the equation to solve for t:

t = sqrt(2d/g)

t = sqrt(2 * 122.5 / 9.8)

t ≈ 5.00 s

So it takes approximately 5.00 seconds for the elevator to fall from the height of 122.5 m.

Now, let's calculate the distance Superguy needs to cover to reach the elevator. The horizontal distance is given as 1.00 km, which is equivalent to 1000 m.

Since the elevator is falling vertically, Superguy needs to cover the diagonal distance which is equivalent to the Pythagorean theorem:

distance = sqrt(horizontal distance^2 + vertical distance^2)

distance = sqrt(1000^2 + 122.5^2)

distance ≈ sqrt(1,000,000 + 15,006.25)

distance ≈ sqrt(1,015,006.25)

distance ≈ 1007.47 m

Superguy needs to cover approximately 1007.47 m.

Finally, we can calculate the average speed using the formula:

average speed = total distance / time

average speed = 1007.47 / 5.00

average speed ≈ 201.49 m/s

Therefore, the answer is B) 5.00 s, 200 m/s.