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Coal is the answer to the question
Answer:
(a) ω = 1.57 rad/s
(b) ac = 4.92 m/s²
(c) μs = 0.5
Explanation:
(a)
The angular speed of the merry go-round can be found as follows:
ω = 2πf
where,
ω = angular speed = ?
f = frequency = 0.25 rev/s
Therefore,
ω = (2π)(0.25 rev/s)
<u>ω = 1.57 rad/s
</u>
(b)
The centripetal acceleration can be found as:
ac = v²/R
but,
v = Rω
Therefore,
ac = (Rω)²/R
ac = Rω²
therefore,
ac = (2 m)(1.57 rad/s)²
<u>ac = 4.92 m/s²
</u>
(c)
In order to avoid slipping the centripetal force must not exceed the frictional force between shoes and floor:
Centripetal Force = Frictional Force
m*ac = μs*R = μs*W
m*ac = μs*mg
ac = μs*g
μs = ac/g
μs = (4.92 m/s²)/(9.8 m/s²)
<u>μs = 0.5</u>
Answer:
D. 2
Explanation:
The skydiver will reach terminal velocity when gravity = air resistance. When this occurs, he/she will no longer accelerate and his/her speed will be constant.
Once the skydiver opens the parachute, his/her speed will decrease suddenly, and again the air resistance increases due to the parachute's large area. Eventually, gravity will equal air resistance again and terminal velocity will be reached for the second time.
Even though the speeds are different, the first terminal velocity is much higher than the second one, this question refers to how many times terminal velocity is reached, not how many times the skydiver accelerates.
Answer:
B, B (decreases, a clockwise)
Explanation:
Finally, the switch on the electromagnet is reopened. The magnitude of the external magnetic flux through the wire loop <u>decreases</u>, and there is <u>a clockwise</u>, current induced in the loop (as seen from the left).