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marta [7]
2 years ago
3

A horizontal uniform plank is supported by ropes I and II at points P and Q, respectively, as shown above. The two ropes have ne

gligible mass. The tension in rope I is 150 N. The point at which rope II is attached to the plank is now moved to point R halfway between point Q and point C, the center of the plank. The plank remains horizontal. What are the new tensions in the two ropes?
The answer is T1=100N and T2=200N but I don't know the steps to solve this one. An explanation would be much appreciated.

Physics
1 answer:
umka21 [38]2 years ago
8 0

Explanation:

There are three forces on the plank.  T₁ pulling up at point P, T₂ pulling up at point Q, and W pulling down at point C.

Let's say the length of the plank is L.

Sum of forces in the y direction before rope II is moved:

∑F = ma

150 N + 150 N − W = 0

W = 300 N

Sum of moments about point P after rope II is moved:

∑τ = Iα

(T₁) (0) − (300 N) (L/2) + (T₂) (3L/4) = 0

-(300 N) (L/2) + (T₂) (3L/4) = 0

-(300 N) (1/2) + (T₂) (3/4) = 0

-150 N + 3/4 T₂ = 0

T₂ = 200 N

Sum of forces in the y direction:

∑F = ma

T₁ + 200 N − 300 N = 0

T₁ = 100 N

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Answer:

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3 0
2 years ago
A car travels 30 miles in 1 hour on a winding mountain road. Which of the following is a true statement?
siniylev [52]

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The true statement is:

"(C) The magnitude of the average velocity is equal to 30 m.p.h."

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Given that a car travels 30 miles in 1 hour on a winding mountain road.

Let' check all the statements one by one:

(A) The magnitude of the total displacement is larger than the distance traveled.

Since the entire motion of the car is not exactly given in the question, so it is not possible to tell whether the magnitude of the total displacement is larger than the distance traveled or not.

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(B) The magnitude of the average velocity is greater than 30 m.p.h.

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Total time taken by the car to cover this distance = 1 hour.

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Thus, this statement is also not true.

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