Superman must stop a 120km/h train in 150m to keep it from hitting a stalled car on the tracks.If the train's mass is 3.6x10^5kg,how much force must he exert?Compare to the weight of the train (give as%).

120 *10^3 meters/3600 seconds = 33.33 m/s

easy way - use energy

Force * distance = work = change in (1/2)mv^2

F (150) = (1/2)(3.6*10^5)(33.33)^2

F = 2000 * 10^5 = 2 *10^8 Newtons

Weight = m g = 3.6*10^5 * 9.81
= 35.3 *10^5

100 * F/weight = 10^2 * 2*10^8/35.3*10^5

= .0566 * 10^5 = 5660 percent for what that is worth :)

wow

wow

i dont understand that question at all

To determine the force Superman must exert to stop the train, we will use Newton's second law of motion, which states that force is equal to mass multiplied by acceleration (F = m * a).

First, we need to calculate the acceleration of the train. We can use the kinematic equation v^2 = u^2 + 2as, where v is the final velocity (0 m/s since the train needs to stop), u is the initial velocity (120 km/h), a is the acceleration, and s is the distance covered.

Converting the initial velocity to meters per second:
120 km/h = (120 * 1000) / 3600 = 33.33 m/s

Rearranging the kinematic equation to solve for acceleration:
0 = (33.33)^2 + 2 * a * 150
0 = 1111.12 + 300a
300a = -1111.12
a = -1111.12 / 300
a = -3.70 m/s^2

Now, we can calculate the force using the mass of the train:
F = m * a
F = (3.6 * 10^5) * (-3.70)
F = -1.332 * 10^6 N

The force Superman must exert to stop the train is -1.332 * 10^6 Newtons. Note that the negative sign indicates that the force is acting in the opposite direction to the train's motion.

To compare this force to the weight of the train, we can calculate the weight of the train using the formula weight = mass * gravity. Assuming the acceleration due to gravity is 9.8 m/s^2:
Weight of the train = (3.6 * 10^5) * 9.8
Weight of the train = 3.528 * 10^6 N

To find the percentage, we divide the force exerted by the weight of the train and multiply by 100:
Percentage = (1.332 * 10^6) / (3.528 * 10^6) * 100
Percentage = 37.8%

Therefore, Superman must exert a force that is approximately 37.8% of the weight of the train to stop it from hitting the stalled car.