Explanation:
Power output of the bulb:
0.021 × 60 W = 1.26 W
Energy produced by the bulb in 1 second:
E = Pt
E = (1.26 W) (1 s)
E = 1.26 J
Round as needed.
Since we have 15 kilometers per hour, and we're looking for 20 minutes, let's set up proportions.
20/60 minutes = x/15
20/60 = 1/3, so let's leave that simplified.
1/3 = x/15
Look at the denominators, 3 to 15 is a factor of 5, so multiply the numerator by 5.
1 • 5 = 5, so you will cover 5 kilometers in 20 minutes.
I hope this helps!
The same braking force does work on these objects to slow them down. The work done is equal to their change in kinetic energy:
FΔx = 0.5mv²
F = force, Δx = distance traveled, m = mass, v = speed
Isolate Δx:
Δx = 0.5mv²/F
Calculate Δx for each object.
Object 1: m = 4.0kg, v = 2.0m/s
Δx = 0.5(4.0)(2.0)²/F = 8/F
Object 2: m = 1.0kg, v = 4.0m/s
Δx = 0.5(1.0)(4.0)²/F = 8/F
The two objects travel the same distance before stopping.
