As air is heated, the particles speed up and spread out (becoming less dense). Hot air balloon pilots can change the balloon’s a
ltitude (up or down) by turning a heater at the base of the balloon on or off. - If you were piloting a hot air balloon, do you think you would turn the heater ON or OFF to make the balloon go up in the air? WHY do you think that?
1 answer:
Answer:
Turn the heater on
Explanation:
There are two main forces involved in a balloon flight
The downward force is the total weight of the balloon: the air it contains, the gas bag, the basket, the passengers, etc.
The upward force is the weight of the of the air the balloon displaces.
During level flight ,
buoyant force = weight of displaced air - total weight of balloon
If you increase the temperature of the air in the bag, the air molecules spread out and leave through the bottom of the bag.
The balloon still has the same volume, so the weight of displaced outside air stays the same.
However, the balloon has lost some hot inside air, so its total weight decreases.
The upward force is greater than the downward force, so the balloon rises.
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Answer:
Explanation:
We have,
The surface temperature of the star is 60,000 K
It is required to find the wavelength of a star that radiated greatest amount of energy. Wein's displacement law gives the relation between wavelength and temperature such that :
Here,
= wavelength
So, the wavelength of the star is .
The correct answer to the question is : 9375 N.
CALCULATION:
As per the question, the mass of the car m = 1500 Kg.
The diametre of the circular track D = 200 m.
Hence, the radius of the circular path R =
=
= 100 m.
The velocity of the truck v = 25 m/s.
When a body moves in a circular path, the body needs a centripetal force which helps the body stick to the orbit. It acts along the radius and towards the centre.
Hence, the force acting on the car is centripetal force.
The magnitude of the centripetal force is calculated as -
Force F =
=
= 9375 N. [ANS}
The centripetal force is provided to the car in two ways. It is the friction which provides the necessary centripetal force. Sometimes friction is not sufficient. At that time, the road is banked to some extent which provides the necessary centripetal force.