Physics, 13.01.2021 17:50, lilakatedancer
For years, space travel was believed to be impossible because there was nothing that rockets could push off of in space in order to provide the propulsion necessary to accelerate. This inability of a rocket to provide propulsion is because ... a. ... space is void of air so the rockets have nothing to push off of. b. ... gravity is absent in space. c. ... space is void of air and so there is no air resistance in space. d. ... nonsense! Rockets do accelerate in space and have been able to do so for a long time. Many people are familiar with the fact that a rifle recoils when fired. This recoil is the result of action-reaction force pairs. A gunpowder explosion creates hot gases that expand outward allowing the rifle to push forward on the bullet. Consistent with Newton's third law of motion, the bullet pushes backward upon the rifle. The acceleration of the recoiling rifle is ... a. greater than the acceleration of the bullet. b. smaller than the acceleration of the bullet. c. the same size as the acceleration of the bullet. In the top picture (below), Kent Budgett is pulling upon a rope that is attached to a wall. In the bottom picture, Kent is pulling upon a rope that is attached to an elephant. In each case, the force scale reads 500 Newton. Kent is pulling ... a. with more force when the rope is attached to the wall. b. with more force when the rope is attached to the elephant. c. the same force in each case
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