Using energy considerations, calculate the average force a 60.0-kg sprinter exerts backward on the track to accelerate from 2.00 to 8.00 m/s in a distance of 25.0 m, if he encounters a headwind that exerts an average force of 30.0 N against him.

F = 102 N

Explanation:

ASSUMING the track is horizontal to avoid gravity potential energy considerations.

The work of the applied force must overcome friction work and increase the kinetic energy of the runner

F(d) = Ff(d) + ½m(v² - u²)

F = Ff + m(v² - u²) / 2d

F = 30.0 + 60.0(8.00² - 2.00²) / (2(25.0))

F = 102 N

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.

momentum of soft ball three times less than baskey ball