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When we talk about the concept of applied force, we're referring to the force that is deliberately applied to an object to make it move or change its motion. In this exercise, the block is pushed with an applied force of 16.0 N. However, this force is not applied directly horizontally. It is angled 25.0 degrees below the horizontal, which affects how we calculate the work done. When calculating the work done by this force, we use the formula:

• \( W_A = F \times d \times \cos(\theta) \)

This formula accounts for the fact that only the component of the force in the direction of the movement contributes to the work done. Here, \( F \) is the force (16.0 N), \( d \) is the displacement (2.20 m), and \( \theta \) is the angle (25 degrees). The cosine function helps us find the component of the force in the direction of motion, making sure our calculations are accurate. By doing these calculations, students will discover how angles affect the efficiency of force applied in moving objects.

Normal force is the force exerted by a surface perpendicular to the object resting on it. It is the table pushing back up on the block to support it against gravity. In this case, as the block moves across the table, the normal force acts perpendicularly to the block's path of motion. Because normal force is always perpendicular to the object's displacement, the angle between the normal force and displacement is 90 degrees. This is important because when calculating work, the formula uses the cosine of the angle. The cosine of 90 degrees is zero, which means the work done by the normal force in this scenario is zero. Even though the normal force is essential for keeping the block from accelerating towards the ground, it doesn't directly contribute to the block's horizontal movement. This highlights how directionality is a key factor in understanding forces and their effects.

Gravity is a constant force acting on any object with mass, directed towards the center of the Earth. For a block on a table, this force pulls it downwards with an intensity equal to its weight: mass multiplied by the gravitational acceleration, which is approximately 9.81 m/s².In this setup, gravity also acts perpendicularly to the direction of the displacement (horizontal movement) of the block. As with the normal force, when considering the work done by gravity, the angle is 90 degrees. Consequently:

• The work done by gravity is \( W_G = 0 \)

because the gravitational force does not contribute to the horizontal displacement of the block. Examining gravity's role in various scenarios helps students understand how it underpins fundamental principles of physics, such as potential and kinetic energy relationships.

Net force refers to the overall force acting on an object when all individual forces are combined. For this block, the key players are the applied force, the normal force, and gravity. Since normal force and gravity do not perform any work in the horizontal movement of the block due to their perpendicular nature, they do not contribute to the net work done on the block.In situations like this, the net force is effectively the same as the applied force when considering work done. We calculate the work done by the net force the same way we do for the applied force since they are aligned:

• \( W_{Net} = W_A \)

By understanding net force, students learn to evaluate multiple forces acting simultaneously, comprehend their individual contributions, and determine the overall movement effects on an object. This is crucial for solving real-world physics problems where multiple forces complicate simple analyses.