Answer:
The speed of Susan is 2.37 m/s
Explanation:
To visualize better this problem, we need to draw a free body diagram.
the work is defined as:

here we have the work done by Paul and the friction force, so:


Now the change of energy is:

Sea scorpions or Eurypterids lived about 251.9 million years ago. They were formidable predators and hunters, but they were wiped out in the Great Permian Mass Extinction, which is also known as the Great Dying (96% of all species on Earth went extinct).The largest species like Jaekelopterus was over 7 feet long! They were mainly thought to go extinct because of a slew of natural disasters that occurred when a comet hit the Earth, as well as increased volcanic activity polluting the seas that Sea scorpions lived in, as well as rising sea temperatures. The Silurian, when these Sea scorpions proliferated was when the water was cooler, holding in more nutrients, allowing both Sea Scorpions and other animals to spread all over the world. But as the oceans became polluted from the volcanoes (and the ash they produced) and the global ocean temperatures began to rise, many animals may not have been able to cope or adapt to the extreme change, becoming helpless in their nutrient deficient water (compared to what they were used to).
I hope this helps!
To solve this problem it is necessary to apply the concepts related to Dopler's Law. Dopler describes the change in frequency of a wave in relation to that of an observer who is in motion relative to the Source of the Wave.
It can be described as

c = Propagation speed of waves in the medium
= Speed of the receiver relative to the medium
= Speed of the source relative to the medium
Frequency emited by the source
The sign depends on whether the receiver or the source approach or move away from each other.
Our values are given by,
Velocity of car
velocity of motor
Velocity of sound
Frequency emited by the source
Replacing we have that



Therefore the frequency that hear the motorcyclist is 601.7Hz
Answer:
1. 21.66 Ohms
2. 3.38 A
3. 6.7 V
Explanation:
1. Req = 6+2 = 8 Ohms (2 and 6 are in a series circuit)
Req = 1/8 +1/4 = 3/8 = 8/3 = 2.66 Ohms (8 and 4 are parallel, so we will add them using this equation)
Req = 2.66 + 1 + 9 + 3 + 6 = 21.66 Ohms
2. I = V/R = 9/2.66 = 3.38 A (In a series circuit, the current is the same across the resistors, so we will add them and divided them by 9 volts)
3. V = IR = 3.38 x 2 = 6.7 V (In a series circuit, the voltage is different, so each resistor will have a different voltage.)
I hope this helps. I am not an expert in physics but its ok :)
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