Wednesday November 1
Mechanical Energy – Forms of Energy
𝑲𝒊𝒏𝒆𝒕𝒊𝒄 𝑬𝒏𝒆𝒓𝒈𝒚 = 𝟎. 𝟓 × 𝒎𝒂𝒔𝒔 × (𝒗𝒆𝒍𝒐𝒄𝒊𝒕𝒚)𝟐
𝑲𝑬 = 𝟎. 𝟓 × 𝒎 × 𝒗𝟐
16. A baseball with a mass of 0.15 kg is moving at a speed of 40.0 m/s. What is the baseball’s kinetic energy from this motion?
17. A 1,500-kg car doubles its speed from 50 km/h to 100 km/h. By how many times does the kinetic energy from the car’s
forward motion increase?
Use your understanding of kinetic energy to answer the following questions.
1.
Determine the kinetic energy of a 625-kg roller coaster car that is moving with a speed of 18.3 m/s.
2.
If the roller coaster car in the above problem were moving with twice the speed, then what would be its new kinetic
energy?
3.
Missy Dewater, the former platform diver for the Ringling Brother's Circus, had a kinetic energy of 12 000 J just prior
to hitting the bucket of water. If Missy's mass is 40 kg, then what is her speed?
Potential Energy
Gravitational Potential Energy
.
𝑷𝒐𝒕𝒆𝒏𝒕𝒊𝒂𝒍 𝑬𝒏𝒆𝒓𝒈𝒚 = 𝒎𝒂𝒔𝒔 × 𝒈 × 𝒉𝒆𝒊𝒈𝒉𝒕
𝑷𝑬 = 𝒎 × 𝒈 × 𝒉
To determine the gravitational potential energy of an object, a zerobe arbitrarily assigned. Typically, the ground is considered to be a
height position must first
position of zero height.
During the swing the gravitational potential energy is changing
Since the height is changing.
18. An 8.0-kg history textbook is placed on a 1.25-m high desk. How large is the gravitational potential energy of the textbookEarth system relative to the floor?
19. Challenge How large is the GPE of the textbook-Earth system in problem 18, relative to the desktop?
25. Calculate GPE A 0.50-kg apple is 2.0 m above the reference level. What is the GPE of the apple-Earth system?