Answer:
You are exactly right. The molecules in hot air are moving faster than the molecules in cold air. Because of this, the molecules in hot air tend to be further apart on average, giving hot air a lower density. That means, for the same volume of air, hot air has fewer molecules and so it weighs less
Level 1: Plants and algae make their own food and are called producers. Level 2: Herbivores eat plants and are called primary consumers.
Answer:
(A) Impulse = 9Ns
(B) F = 1286N
Explanation:
Impulse = change in momentum = m(v-u)
v = 0 (the hand comes to a stop)
u = -10m/s
Mass = 0.9kg
Impulse = 0.9 ×(0- (-10))
= 9Ns
(B) F×t = Impulse
F = Impulse/ t
t = 7ms = 7×10-³
F = 9/ (7×10-³)
F = 1286N.
Answer:
A tsunami with a record run-up height of 1720 feet occurred in Lituya Bay, Alaska. On the night of July 9, 1958, an earthquake along the Fairweather Fault in the Alaska Panhandle loosened about 40 million cubic yards (30.6 million cubic meters) of rock high above the northeastern shore of Lituya Bay.
Explanation:
Back emf is 85.9 V.
<u>Explanation:</u>
Given-
Resistance, R = 3.75Ω
Current, I = 9.1 A
Supply Voltage, V = 120 V
Back emf = ?
Assumption - There is no effects of inductance.
A motor will have a back emf that opposes the supply voltage, as the motor speeds up the back emf increases and has the effect that the difference between the supply voltage and the back emf is what causes the current to flow through the armature resistance.
So if 9.1 A flows through the resistance of 3.75Ω then by Ohms law,
The voltage across the resistance would be
v = I x R
= 9.1 x 3.75
= 34.125 volts
We know,
supply voltage = back emf + voltage across the resistance
By plugging in the values,
120 V = back emf + 34.125 V
Back emf = 120 - 34.125
= 85.9 Volts
Therefore, back emf is 85.9 V.
