Let T be the force exerted on the rope by her. This force induces tension in the rope, which exerts an upward force on the crates, while the weight of the crate pulls downward. Thus, the net force acting on the crate can be expressed as mg - T, acting in the downward direction. According to Newton's law, we can set up the equation: mg - T = ma. Given that a = 0 (the speed remains constant), this simplifies our equation to mg - T = 0, which leads to T = mg. Therefore, T = 25 x 9.8 = 245 N, indicating that the force she needs to apply is 245 N.
Answer:
Explanation:
As the baseball ascends, gravitational forces as well as air resistance act downward, whereas the displacement is moving upward which results in an angle of 180° between the force and displacement. Therefore, the work done by both the gravitational force and air resistance is negative, confirming option (d) as accurate.
Answer:

Explanation:
The beacon is rotating at an angular speed of

so we have



We know that

At this point we have


So we can conclude with


Answer:
Maximum emf = 5.32 V
Explanation:
Provided data includes:
Number of turns, N = 10
Radius of loop, r = 3 cm = 0.03 m
It made 60 revolutions each second
Magnetic field, B = 0.5 T
We are tasked to determine the maximum emf produced in the loop, which is founded on Faraday's law. The induced emf can be calculated by:

For the maximum emf, 
Therefore,

Hence, the maximum emf generated in the loop is 5.32 V.
Answer:
A) and B) are valid.
Explanation:
When an object remains at rest, it is indicative that no net force acts upon it.
The downward gravitational force from Earth must be counterbalanced by an upward force of equal magnitude in order to maintain rest.
This upward force is provided by the normal force, which adjusts to satisfy Newton’s 2nd Law and is always perpendicular to the surface supporting the object (in this instance, the ground).
At the molecular level, this normal force comes from the ground's bonded molecules acting like tiny springs, compressed by the object’s molecules, providing an upward restorative force.
Thus, statements A) and B) are true.