A 5000-kg freight car runs into a 10,000-kg freight car at rest. They couple upon collision and move with a speed of 2 m/s. What
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Answer:
The current is reduced to half of its original value.
Explanation:
- Assuming we can apply Ohm's Law to the circuit, as the internal resistance and the load resistor are in series, we can find the current I₁ as follows:
- where Rint = r and RL = r
- Replacing these values in I₁, we have:
- When the battery ages, if the internal resistance triples, the new current can be found using Ohm's Law again:
- We can find the relationship between I₂, and I₁, dividing both sides, as follows:
- The current when the internal resistance triples, is half of the original value, when the internal resistance was r, equal to the resistance of the load.
Answer:
Question 1)
a) The speed of the drums is increased from 2 ft/s to 4 ft/s in 4 s. From the below kinematic equations the acceleration of the drums can be determined.
This is the linear acceleration of the drums. Since the tape does not slip on the drums, by the rule of rolling without slipping,
where α is the angular acceleration.
In order to continue this question, the radius of the drums should be given.
Let us denote the radius of the drums as R, the angular acceleration of drum B is
α = 0.5/R.
b) The distance travelled by the drums can be found by the following kinematics formula:
One revolution is equal to the circumference of the drum. So, total number of revolutions is
Question 2)
a) In a rocket propulsion question, the acceleration of the rocket can be found by the following formula:
b)