6th Grade Chapter 7 Section 1 Quiz

Explanation
When a force produces motion parallel to the direction of the force, work is done in the scientific sense. Work is defined as the transfer of energy that occurs when an object is moved by a force applied in the direction of motion. In this scenario, since there is motion parallel to the force, there is a displacement of the object and work is being done. Power, on the other hand, is the rate at which work is done or energy is transferred. Motion, while related, does not specifically refer to the transfer of energy or the concept of work.

Explanation
When force is at a right angle to the direction of motion, the force does not work. This is because the force and the direction of motion are perpendicular to each other, resulting in no work being done. Work is defined as the product of force and displacement, and when the force is perpendicular to the displacement, the dot product of the two vectors becomes zero, indicating no work done.

Explanation
When you pick up a book bag, you are exerting a force against gravity to lift the bag. This force is in the same direction as the displacement of the bag, resulting in positive work. Work is defined as the product of force and displacement in the direction of the force, and since the force and displacement are in the same direction when picking up a book bag, the work done is positive.

Explanation
Friction does negative work on a sled because it acts in the opposite direction to the motion of the sled. As the sled moves forward, the frictional force opposes this motion, causing a loss of energy. This loss of energy is considered negative work because it reduces the sled's overall mechanical energy.

Explanation
When you pull a sled, you are applying a force in the same direction as the displacement of the sled. This means that you are doing positive work on the sled. Work is defined as the product of force and displacement, and since both the force and displacement are in the same direction, the work done is positive.

Explanation
When the motion is in the direction of the force, positive work is done. This means that the force applied is in the same direction as the displacement of the object. In other words, the force is helping the object move in the same direction, resulting in positive work being done.

Explanation
When the motion is opposite to the direction of the force, negative work is done. This is because work is defined as the product of force and displacement in the direction of the force. When the motion is opposite to the force, the displacement is in the opposite direction, resulting in a negative value for work. This indicates that energy is being transferred out of the system, rather than being added to it.

Explanation
Carrying a ball off the field does not involve any transfer of energy or displacement in the direction of the applied force. Therefore, no work is done in this scenario.

Explanation
The formula for work is W = Fd, where W represents work, F represents force, and d represents distance. This formula calculates the amount of work done on an object when a force is applied to move it a certain distance. By multiplying the force and the distance, we can determine the work done.

Explanation
Work is measured in joules (J). Joules are a unit of energy and work is the transfer of energy. Therefore, work is measured in joules as it represents the amount of energy transferred or expended in performing a task or exerting a force over a distance.

Explanation
The correct answer is 1 kg * m2/s2. This is because the unit of energy is joule (J), which is equivalent to 1 kg * m2/s2. Therefore, 1 J is the same as 1 kg * m2/s2.

Explanation
The work done is calculated by multiplying the force applied with the distance traveled in the direction of the force. In this case, the force applied is 100 N and the distance traveled is 1000 m. Therefore, the work done is 100 N * 1000 m = 100,000 N*m = 100,000 J.

Explanation
Power is the correct answer because it is the measure of the rate at which work is done or the amount of work done per unit of time. It is calculated by dividing the work done by the time taken to do the work. Force and speed are not accurate descriptions of the rate at which work is being done.

Explanation
The formula for power is P = W/t. This formula states that power is equal to work divided by time. Work (W) is defined as the product of force (F) and distance (d) traveled. However, the given equations r = d/t and r = W/t are not relevant to the formula for power.

Explanation
Power is the rate at which work is done or energy is transferred. It is measured in watts (W). Watts represent the amount of energy transferred or work done per unit of time. Therefore, watt is the appropriate unit for measuring power.

Explanation
The correct answer is 1 J/s because the unit of power is measured in watts (W), which is defined as the rate at which work is done or energy is transferred. Therefore, 1 W represents the transfer of 1 joule (J) of energy per second (s).