Answer:
1) 3.92 J
2) 1596.08 J
3) 16.3 s ??
Explanation:
Initial Potential energy PE = mgh = 0.5(9.8)(0) = 0 J
Initial Kinetic energy KE = ½mv² = ½(0.5)80² = 1600 J
PE = 0.5(9.8)(0.80) = 3.92 J
KE = 1600 - 3.92 = 1596.08 J
Question 3 is not clear
to the point 80 cm above the ground the flight time is only 0.01 s
The time when the mass strikes ground again will be twice the time gravity takes to reduce the initial velocity to zero
t = 2(80.0 / 9.8) = 16.3 s
would not 80 m above the ground be a much more interesting point to consider?
PE = 0.5(9.8)(80) = 392 J
KE = 1600 - 392 = 1208 J
v₈₀ = √(2(1280) /0.5) = 69.5 m/s
t₈₀ = h/v(avg) = 80 / (½(80 + 69.5)) = 1.07 s
Answer:
Energy Flows Quick check answers:
1. Ffd.
2. The kinetic energy decreases, and gravitational potential energy increases.
3. The internal energy of the system increases.
4. KEbox= Etotal-mgh
5. Etotal = 1/2m1(v1)^2+1/2m^2(v2)^2+U
Answer:
Explanation:
Car is 25 m long . worker moves at speed 3.0 m/s with respect to the car
Time taken to reach the other end
= 25 / 3 = 8.333 s
Displacement of flatcar during this period
= 7 x 8.333
= 58.33 m
Answer:
D. n=6 to n=2
Explanation:
Given;
energy of emitted photon, E = 3.02 electron volts
The energy levels of a Hydrogen atom is given as; E = -E₀ /n²
where;
E₀ is the energy level of an electron in ground state = -13.6 eV
n is the energy level
From the equation above make n, the subject of the formula;
n² = -E₀ / E
n² = 13.6 eV / 3.02 eV
n² = 4.5
n = √4.5
n = 2
When electron moves from higher energy level to a lower energy level it emits photons;
For a photon to be emitted, electron must move from higher energy level to a lower energy level. The higher energy level is 6 while the lower energy level is 2
Therefore, The electron energy-level transition is from n = 6 to n = 2
