1. How much work or energy (in J) does a 150 W light bulb convert to heat and light in 1.0 h?
2.The force of gravity on a box of apples is 98.0 N. How much work will you do (a) if you lift the box from the floor to a height of
1.2 m?
(b if you carry the box horizontally a distance of 2.0 m?
1 work=powerinWatts*timeinseconds
2. work up=mgh
horizonatlly, h is sero.
540,000 J
1. To calculate the amount of work or energy converted by a light bulb, we need to multiply its power (in watts) by the time (in seconds) for which it operates. Since the provided time is given in hours, we will convert it to seconds later in the calculation.
Given:
Power of the light bulb (P) = 150 W
Time (t) = 1.0 h
First, we need to convert the time from hours to seconds:
Time in seconds = 1.0 h × (3600 s/h) = 3600 s
Now we can calculate the energy converted by the light bulb using the formula:
Energy (E) = Power × Time
Energy = 150 W × 3600 s = 540,000 J
Therefore, a 150 W light bulb converts 540,000 J of work or energy to heat and light in 1.0 hour.
2. When lifting an object against gravity, the work done is given by the formula:
Work (W) = Force × Distance × cos(θ)
(a) To calculate the work done when lifting the box to a height of 1.2 m, we need the force and the distance lifted.
Given:
Force (F) = 98.0 N
Distance (d) = 1.2 m
Angle between the force and direction of motion (θ) = 0° (since lifting straight up)
Plugging in the values into the formula:
Work = 98.0 N × 1.2 m × cos(0°) = 117.6 J
Therefore, the work done in lifting the box to a height of 1.2 m is 117.6 J.
(b) When carrying the box horizontally, no vertical lifting is involved, so the force does no work on the horizontal displacement. The work done is given by the formula:
Work (W) = Force × Distance × cos(θ)
Given:
Force (F) = 98.0 N
Distance (d) = 2.0 m
Angle between the force and direction of motion (θ) = 90° (since the force is perpendicular to the motion)
Plugging in the values into the formula:
Work = 98.0 N × 2.0 m × cos(90°) = 0 J
Therefore, no work is done when carrying the box horizontally a distance of 2.0 m.