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What is the effect of a 180° angle between force and displacement on the work done?
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The work done will be negative because cos(180°) = -1, indicating that energy is removed from the system.
Describe an example where the angle between force and displacement is 180°.
When a box is pushed in one direction while friction acts in the exact opposite direction, making the angle 180°.
What is the net force acting on the box if it is pushed by a 10 N force and opposed by a 4 N frictional force?
Net force, F_net = 10 N - 4 N = 6 N
What is the formula for work (W) in terms of force (F), displacement (d), and angle (θ)?
W = F × d × cos(θ)
Describe the formula for net work (W_net).
W_net = F_net × d × cos(θ)
How do you determine the net work added to a box pushed with a force of 10 N and opposed by a frictional force of 4 N over 10 meters?
Net work = 100 J (pushed) - 40 J (friction) = 60 J
Why does a box speed up if the net work done on it is positive?
Positive net work indicates that energy is being added to the box, causing an increase in its kinetic energy and speed.
Calculate the net work done when a net force of 6 N acts over a displacement of 10 meters.
W_net = 6 N × 10 m × cos(0°) = 60 J
When is work done by a force considered zero?
Work is zero when the force is perpendicular to the direction of displacement (θ = 90°, cos(90°) = 0).
How do you calculate the work done by a 10 N force pushing a box 10 meters to the right?
W = 10 N × 10 m × cos(0°) = 100 J
If a box is moving on a frictionless floor and encounters a rough section with a frictional force, what type of work is done and why?
Negative work is done because the frictional force opposes the motion, removing energy from the box.
In Example 2, what happens to the box encountering a rough section with a 4 N friction force over 10 m?
The box will slow down because the work done by friction (W = -40 J) removes energy from the box.
What is the cosine of 0° and how does it affect the work calculation?
cos(0°) = 1, which means the entire force contributes to the work done since force and displacement are in the same direction.
What does a negative work value imply in terms of energy?
Negative work implies that energy is being removed from the system, causing a decrease in the object's kinetic energy.
Calculate the work done by friction if the frictional force is 4 N and the displacement is 10 m.
W = 4 N × 10 m × cos(180°) = -40 J
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