A planet follows an elliptical orbit that brings it as close as 21 million km to a star and as far as 75 million km from the star. At both of these locations the velocity of the planet makes a right angle to the direction to the star. If the planet's speed is 38 km/s when it is farthest from the star, how fast is it moving when it is closest to the star

Explanation:

In an elliptical orbit , the angular momentum of the planet remains constant because velocity of planet makes a right angle to the direction to the star .

mvr = constant .

mv₁r₁ = mv₂r₂

v₁r₁ = v₂r₂

v₁ x 21 = 38 x 75

v₁ = 135.71 km/s .

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.