Question

A 1000 kg railroad car is initially empty when it is rolled under a water-dispensing tank. The tank begins to dispense 500 kg of water every second into the railroad car from a height 5 meters above the floor of the car. What normal force does the track exert on the car 8 seconds after water first strikes the floor of the car?

Answer 1

The normal force exerted by the track on the railroad car 8 seconds after water first strikes the floor is 49000 Newtons, calculated by multiplying the total mass (the sum of the car's initial mass and the mass of water added) by the acceleration due to gravity.

Step-by-step explanation:

The student's question involves calculating the normal force exerted by the track on a railroad car that is being loaded with water. To find this, we need to consider the weight of the railroad car, the weight of the water added, and the force of gravity.

After 8 seconds, 4000 kg of water (500 kg/s × 8 s) will have been dispensed into the car.

The total weight at this moment is the sum of the weight of the water and the car, which is (1000 kg + 4000 kg) × 9.8 m/s².

Therefore, the normal force exerted by the track is equal to the gravitational force on this total mass.

This can be calculated as follows:

• Total mass = 1000 kg (car) + 4000 kg (water) = 5000 kg
  Gravitational force (Weight) = total mass × acceleration due to gravity
  Gravitational force (Weight) = 5000 kg × 9.8 m/s²
  Gravitational force (Weight) = 49000 N

Thus, the normal force exerted by the track is 49000 Newtons.