1.a paddle boat is propelled to the left in the figure above by a wheel of nine flat blades that rotate about a central axis. which of the following is correct?
A) The wheel should rotate in a clockwise (CW) direction because the force exerted on the water by the blade is in the direction opposite to the force exerted by the blade on the water.
B)The wheel should rotate in a counterclockwise (CCW) direction because the force exerted on the water by the blade is in the direction opposite to the force exerted by the blade on the water.
C)The wheel should rotate in a counterclockwise (CCW) direction because the force exerted on the water by the blade is in the direction opposite to the force exerted by the blade on the water.
D)The wheel should rotate in a clockwise (CW) direction because the force exerted on the water by the blade is in the direction exerted by the blade on the water.
2.As shown above an adhesive has been applied to contacting faces of two blocks so that the blocks interact with an adhesive force that has a magnitude, F Adhesion . A tension, T , is exerted by a wire attached to the upper blocks causing the blocks to remain at rest. The two blocks have weights, W Bottom and W Top . Which of the following must be true?
A) T=Wbottom+Wtop+Fadhesion
B)T=Wtop-Fadhesion
C)Wbottom=Fadhesion
D)Wtop=T
1. B)The wheel should rotate in a counterclockwise (CCW) direction because the force exerted on the water by the blade is in the direction opposite to the force exerted by the blade on the water.
2. A) T=Wbottom+Wtop+Fadhesion
1. The correct answer is A) The wheel should rotate in a clockwise (CW) direction because the force exerted on the water by the blade is in the direction opposite to the force exerted by the blade on the water.
2. The correct answer is A) T = Wbottom + Wtop + Fadhesion.
1. In order to determine the correct answer, let's understand the concept of Newton's third law of motion. According to Newton's third law, for every action, there is an equal and opposite reaction.
In the case of a paddle boat, when the blades rotate and push against the water, they create a force on the water. As a reaction to this force, the water exerts an equal and opposite force on the blades.
Now, considering the direction of forces, if the blades push the water to the left, then the water will push back on the blades to the right. This means that the force exerted on the water by the blade is in the opposite direction to the force exerted by the blade on the water.
So, with this understanding, let's check the given options:
A) The wheel should rotate in a clockwise (CW) direction because the force exerted on the water by the blade is in the direction opposite to the force exerted by the blade on the water.
This option is incorrect because it suggests that the wheel should rotate in a clockwise direction, which is not the case.
B) The wheel should rotate in a counterclockwise (CCW) direction because the force exerted on the water by the blade is in the direction opposite to the force exerted by the blade on the water.
This option is correct because it suggests that the wheel should rotate in a counterclockwise direction, which aligns with the concept of Newton's third law.
C) The wheel should rotate in a counterclockwise (CCW) direction because the force exerted on the water by the blade is in the direction opposite to the force exerted by the blade on the water.
This option is a repetition of option B and carries the same rationale.
D) The wheel should rotate in a clockwise (CW) direction because the force exerted on the water by the blade is in the direction exerted by the blade on the water.
This option suggests that the wheel should rotate in a clockwise direction, which is not aligned with the concept of Newton's third law.
Therefore, the correct answer is B) The wheel should rotate in a counterclockwise (CCW) direction because the force exerted on the water by the blade is in the direction opposite to the force exerted by the blade on the water.
2. In this question, we need to determine the relationship between the tension (T), the weight of the bottom block (Wbottom), the weight of the top block (Wtop), and the adhesive force (Fadhesion).
First, let's consider the forces acting on the blocks. The weight of the bottom block, Wbottom, acts downward. The weight of the top block, Wtop, also acts downward. The tension, T, acts upward.
Since the blocks are at rest, the forces must be balanced.
Now, let's think about the adhesive force. The adhesive force acts between the two blocks and opposes their separation. Therefore, it acts upward.
To balance the forces, the tension force, T, must be equal to the total downward forces (Wbottom + Wtop) plus the upward adhesive force (Fadhesion).
Let's check the options:
A) T = Wbottom + Wtop + Fadhesion
This option correctly states that the tension is equal to the sum of the weights of both blocks plus the adhesive force. So, option A is correct.
B) T = Wtop - Fadhesion
This option suggests that the tension is equal to the weight of the top block minus the adhesive force. This is incorrect because it does not consider the weight of the bottom block or the need to balance the forces.
C) Wbottom = Fadhesion
This option suggests that the weight of the bottom block is equal to the adhesive force. This is incorrect because it does not account for the tension or the weight of the top block.
D) Wtop = T
This option suggests that the weight of the top block is equal to the tension force. This is incorrect because it does not account for the weight of the bottom block or the adhesive force.
Therefore, the correct answer is A) T = Wbottom + Wtop + Fadhesion.