# Physics #4

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 According to Kepler's laws, the planets orbit the Sun along the paths that are ELLIPSES A rock is trown upward at an angle of 50 degrees with respect to the horizontal. As it rises, neglecting air resistance, the vertical component of its velocity DECREASES A ball is thrown upward at 50 degrees with respect to the horizontal. As it rises, neglecting air resistance, the horizontal component of its velocity DOES NOT CHANGE A stone is thrown horizontally from the top of a cliff. One second after it has left your hand, its vertical distance below the top of the cliff is 5 M A bullet fired horizontally from a rifle begins to fall AS SOON AS IT LEAVES THE BARREL A projectile is launched vertically upward at 50 m/s.If air resistance is negligible, its speed upon returning to its starting point is EXACTLY 50 M/S An Earth satellite is simply a projectile FREELY FALLING AROUND THE EARTH A hunter on level ground fires a bullet at zero-degree angle with the horizontal while simultaneously dropping another bullet from the level of the rifle. Which bullet will hit the ground first? BOTH HIT THE GROUND AT THE SAME TIME An object is dropped and freely falls to the ground with an acceleration of 1g. If it is thrown upward at an angle instead, its acceleration will be 1G DOWNWARD Two projectiles are fired from ground level at equal speeds but different angles. One is fired at an angle of 30 degrees and the other at 60 degrees. Neglecting air resistance, the projectile to hit the ground first will be the one fired at 30 DEGREES A projectile is fired vertically from the surface of the Earth at 8 km/s. The projectile will RISE AND FALL BACK TO THE EARTH'S SURFACE An object is thrown vertically into the air. Because of air resistance, the time for its descent will be LONGER THAN THE ASCENT TIME A river 100 yards wide flows due South at 1 yard per second. A boat that goes at one yard per second relative to the water is pointed due East as it crosses from the West bank. The boat reaches the East bank 100 YARDS FARTHER SOUTH THAN WHERE IT STARTED What prevents satellites such as the space shuttle from falling? NOTHING: THEY ARE CONTINUALLY FALLING AS THEY ORBIT THE EARTH The fastest moving planet in a solar system is THE PLANET NEAREST TO THE SUN A person on the surface of the Earth has a mass of 50 kg and a weight of 490 N. If this person were floating freely inside a space station far away from Earth, she or he would have LESS WEIGHT AND THE SAME MASS Consider a moon that orbits one of our most distant planets in an elliptical path. The distance that the moon covers each day is GREATEST WHEN THE MOON IS CLOSEST TO THE PLANET The speeds of the planets about the Sun depend on THEIR DISTANCE FROM THE SUN The Early Bird communication satellite hovers over the same point on Earth's equator indefinitely. This is because ITS ORBITAL PERIOD IS 24 HOURS Angular momentum is greater for a satellite when it is at the ITS ANGULAR MOMENTUM IS THE SAME AT ANY POINT ON ITS TRACETORY A weightless astronaut in an orbiting shuttle is LIKE THE SHUTTLE, PULLED BY EARTH'S GRAVITATION