Cart a, with a mass of 0.4 kg, travels on a horizontal air track at 6 m/s and hits cart b, which has a mass of 0.8 kg and is initially at rest. after the collision, cart a has a velocity of 2 m/s in the opposite direction. what is the final kinetic energy of cart b

6.4 J

Explanation:

For cart A

mA = 0.4 kg, uA = 6 m/s, vA = - 2 m/s

For cart B

mB = 0.8 kg, uB = 0, vB = ?

use the law of conservation of momentum

momentum of system before coliision = momentum of system after collision

mA uA + mB uB = mA vA + mB vB

0.4 x 6 + 0 = 0.4 x (- 2) + 0.8 x vB

vB = 4 m/s

Kinetic energy of Cart B after collision = 1/2 mB vB^2

                                                                = 1/2 x 0.8 x 4 x 4 = 6.4 J

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.

5 w for 1hr = 5x60x60 joules=300x60=3000x6=18,000j as total energy conversion. efficiency of bulb needed for radiant to thermal within 18000