Answer:
the force of the friction is A-0.52
Using g = 9.8 m/s2, the statement that best describes the roller coaster car when it is at the top of the loop-de-loop is that The car has both potential and kinetic energy, and it is moving at 24.6 m/s.
The correct answer is <span>B) The car has both potential and kinetic energy, and it is moving at 24.6 m/s.</span>
The velocity of the body is zero; option A
<h3>What is the motion of an oscillating body?</h3>
The motion of an oscillating body is known as simple harmonic motion.
Simple harmonic motion involves a periodical motion of a body whose acceleration is directed towards a fixed point.
For a body that is oscillating up and down at the end of a spring, considering when the body is at the top of its up-and-down motion, the velocity of the body at the top and down is zero since the body comes to rest at the top and down position of its motion.
In conclusion, oscillating bodies undergo simple harmonic motion.
Learn more about simple harmonic motion at: brainly.com/question/24646514
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Answer:
The speed of the plank relative to the ice is:

Explanation:
Here we can use momentum conservation. Do not forget it is relative to the ice.
(1)
Where:
- m(g) is the mass of the girl
- m(p) is the mass of the plank
- v(g) is the speed of the girl
- v(p) is the speed of the plank
Now, as we have relative velocities, we have:
(2)
v(g/b) is the speed of the girl relative to the plank
Solving the system of equations (1) and (2)



I hope it helps you!