Answer: A. Work is done on the system and heat is transferred from the system for a net decrease in internal energy.
Explanation:
A refrigerator is a device which dispenses heat from the close system to a warmer area or in the surrounding. By dispensing the heat the internal temperature of the refrigerator drops. The system of refrigerator violates the second law of thermodynamics. As it performs the work to cool the region instead of heating the region. The work is done on the system and the internal energy decreases and the heat energy is liberated to the surrounding area. A refrigerator is an open system.
Answer:
1.8 m/s
Explanation:
momentum = mass × velocity
initial momentum = m1v1+m2v2
= 3×3 +2×0 = 9+0= 9 kg m/s
let combined velocity be V
HENCE
final momentum = total mass × velocity
= (3+2) × V = 5V
According to law of conservation of momentum
final momentum = initial momentum
5V = 9
V =9/5
V = 1.8 m/s
Answer:
kick baseball
Explanation:
The sport of kickball, originally called "kick baseball," has roots going back to the early part of the 20th century in Cincinnati, Ohio. In the 1920's physical education teachers used kickball to teach the basics of baseball
Answer:
Option E is correct.
Time the ball remains in the air before striking the ground is closest to 3.64 s
Explanation:
yբ = yᵢ + uᵧt + gt²/2
yբ = 0
yᵢ = 2 m
uᵧ = u sinθ = 20 sin 60 = 17.32 m/s
g = -9.8 m/s², t = ?
0 = 2 + 17.32t - 4.9t²
4.9t² - 17.32t - 2 = 0
Solving the quadratic equation,
t = 3.647 s or t = -0.1112 s
time is a positive variable, hence, t = 3.647 s. Option E.
