Spiderman stops a train

Question

Background:

Spiders can lift up to 8 times their own bodyweight

The force spiderman exerts is constant over the period of time he attempts to stop the train.

The info given:

The weight of the Train fully loaded is 38000 Kg

The speed of the train is 80 mph

The length of time spiderman exerts a force on the train is 72 seconds.

spiderman weight is 71 Kg

Questions:

1- Determine if it would be possible for spiderman to stop the train.

2- superman once lifted 2x10^20 tons with one hand in 1 second. How many trains can superman stop over the course of 1 second?

Answer 1

First off we must convert 80 mph to meters per second

80 miles/hr (1hr/3600s) (1609 m/1mile) = 35.76 m/s

now to find the acceleration to stop a train in 72 seconds

vf = vi +at

0 m/s = 35.76 m/s + a (72 seconds)

a = 0.466 m/s^2

Now to find out the forces to stop the train:

F = ma

F = (38,000 kg)(0.4966 m/s^2) = 18,871 N

Forces of spiderman is then 8 times his weight so: F = 8 x (71 kg) (9.81 m/s^2) = 5572 N

So that does not appear to be enough forces to stop the train in 72 seconds

Part b is related to superman

first convert the tons to N

2 x10^20 tons x (9964 N/1 ton) = 1.9928 x 10^24 N (this is an insane amount)

to stop 1 train in 1 seconds he would need an acceleration of 35.76 m/s^2

0 = 35.76 + a(1 seconds)

so a forces of: F = 38,000(35.76) = 1358880 N to stop one train

so 1.9928 x 10^24 / 1358880 N = 1.4665 x 10^18 trains