1.what happens to the weight(and normal reaction)of something, in an elevator that accelerates upward.plz explainalso,are action reaction forces still equal?2.What happens when a coin is dropped in an elevator accelerating downward3.What happens to the tension in a rope wound over a pulley with one of its ends attached to an object of weight 75N when the object moves upward with a) increasing b) decreasing speed.

When considering the behavior of weight and normal reaction forces in an elevator, it's essential to understand the principles of physics that govern motion and forces. Let's break down your questions step by step.

1. Weight and Normal Reaction in an Upward Accelerating Elevator

When an elevator accelerates upward, the apparent weight of an object inside the elevator increases. This is due to the additional force required to accelerate the object along with the elevator. The normal force, which is the force exerted by the floor of the elevator on the object, also increases to counteract this additional force.

• Weight: The actual weight of the object remains constant, as it is determined by the gravitational force acting on it (Weight = mass × gravity).
• Normal Force: The normal force can be calculated using the formula: Normal Force = Weight + (mass × acceleration of the elevator). This means that as the elevator accelerates upward, the normal force increases.

Regarding action-reaction forces, according to Newton's third law, they remain equal and opposite. For every action, there is an equal and opposite reaction. So, while the normal force increases, the gravitational force acting on the object does not change, but the forces acting on the elevator itself will adjust accordingly.

2. Coin Dropped in a Downward Accelerating Elevator

When a coin is dropped in an elevator that is accelerating downward, the situation changes significantly. The coin will experience free fall relative to the elevator. Since the elevator is accelerating downward, the coin will appear to fall slower than it would in a stationary elevator.

• Apparent Weightlessness: The coin will not exert a normal force on the floor of the elevator, as both the coin and the elevator are accelerating downward at the same rate. This creates a sensation of weightlessness for the coin.
• Acceleration: If the elevator accelerates downward at a rate equal to the acceleration due to gravity (approximately 9.81 m/s²), the coin will fall alongside the elevator, and it will seem as if it is floating.

3. Tension in a Rope Over a Pulley

Now, let's examine the tension in a rope wound over a pulley when one end is attached to an object weighing 75N, and the object moves upward with varying speeds.

a) Increasing Speed

When the object moves upward with increasing speed, the tension in the rope must not only support the weight of the object but also provide the additional force required for the upward acceleration. The tension can be calculated using the formula:

Tension = Weight + (mass × acceleration)

As the speed increases, the acceleration is positive, leading to a greater tension in the rope.

b) Decreasing Speed

If the object is moving upward but slowing down, it is still moving against gravity, but the acceleration is negative (deceleration). In this case, the tension in the rope will be less than when the object is accelerating upward. The formula remains:

Tension = Weight - (mass × deceleration)

Here, the tension decreases because the upward force required to maintain the motion is less than when the object was accelerating upward.

In summary, the dynamics of forces in an elevator or involving pulleys can be complex, but by applying Newton's laws of motion, we can predict how forces like weight, normal force, and tension behave under different conditions. Understanding these concepts is crucial for analyzing real-world scenarios in physics.