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Answer: 1026s, 17.1m
Explanation:
Given
COP of heat pump = 3.15
Mass of air, m = 1500kg
Initial temperature, T1 = 7°C
Final temperature, T2 = 22°C
Power of the heat pump, W = 5kW
The amount of heat needed to increase temperature in the house,
Q = mcΔT
Q = 1500 * 0.718 * (22 - 7)
Q = 1077 * 15
Q = 16155
Rate at which heat is supplied to the house is
Q' = COP * W
Q' = 3.15 * 5
Q' = 15.75
Time required to raise the temperature is
Δt = Q/Q'
Δt = 16155 / 15.75
Δt = 1025.7 s
Δt ~ 1026 s
Δt ~ 17.1 min
<u>Answers</u>
(a) 6.75 Joules.
(b) 5.27 m/s
(c) 0.75 Joules
<u>Explanation</u>
Kinetic energy is the energy possessed by a body in motion.
(a) its kinetic energy at A?
K.E = 1/2 mv²
= 1/2 × 0.54 × 5²
= 6.75 Joules.
(b) its speed at point B?
K.E = 1/2 mv²
7.5 = 1/2 × 0.54 × V²
V² = 7.5 ÷ 0.27
= 27.77778
V = √27.77778
= 5.27 m/s
(c) the total work done on the particle as it moves from A to B?
Work done = 7.5 - 6.75
= 0.75 Joules
Answer:
Momentum is always conserved, and kinetic energy may be conserved.
Explanation:
For an object moving on a horizontal, frictionless surface which makes a glancing collision with another object initially at rest on the surface, the type of collision experienced by this objects can either be elastic or an inelastic collision depending on whether the object sticks together after collision or separates and move with a common velocity after collision.
If the body separates and move with a common velocity after collision, the collision is elastic but if they sticks together after collision, the collision is inelastic.
Either ways the momentum of the bodies are always conserved since they will always move with a common velocity after collision but their kinetic energy may or may not be conserved after collision, it all depends whether they separates or stick together after collision and since we are not told in question whether or not they separate, we can conclude that their kinetic energy "may" be conserved.
