Mechanics | Relativity Answers

On a planet that has no atmosphere, a rocket 15.8 m tall is resting on its launch pad. Freefall acceleration on the planet is 4.45 m/s2. A ball is dropped from the top of the rocket with zero initial velocity. (a) How long does it take to reach the launch pad? (b) What is the speed of the ball just before it reaches the ground?

A cheetah is traveling across the African countryside, initially moving at a constant velocity of 8.0 m/s. It sees a gazelle at t = 0 seconds and begins to accelerate in a straight line. At t = 4.0 seconds it has a velocity of 23 m/s and then continues to move at this constant velocity. At t = 5.0 seconds, the cheetah is standing still, having knocked over the gazelle.(a) What is the average acceleration of the cheetah from t = 0 to t = 5.0 seconds?

A person throws a ball straight up. He releases the ball at a height of 1.75 m above the ground and with a velocity of 12.0 m/s. Ignore the effects of air resistance. (a) How long until the ball reaches its highest point? (b) How high above the ground does the ball go?

Two rocks are thrown off the edge of a cliff that is 15.0 m above the ground. The first rock is thrown upward, at a velocity of +12.0 m/s. The second is thrown downward, at a velocity of −12.0 m/s. Ignore air resistance. Determine (a) how long it takes the first rock to hit the ground and (b) at what velocity it hits. Determine (c) how long it takes the second rock to hit the ground and (d) at what velocity it hits.

You stand near the edge of Half Dome in Yosemite, reach your arm over the railing, and (thoughtlessly, since what goes up does come down and there are people below) throw a rock upward at 8.00 m/s. Half Dome is 1460 meters high. How long does it take for the rock to reach the ground? Ignore air resistance.

On the Apollo 15 space mission, Commander David R. Scott verified Galileo's assertion that objects of different masses accelerate at the same rate. He did so on the Moon, where the acceleration due to gravity is 1.62 m/s2 and there is no air resistance, by dropping a hammer and a feather at the same time. Assume they were 1.25 meters above the surface of the Moon when he released them. How long did they take to land?

You are a bungee jumping fanatic and want to be the first bungee jumper on Jupiter. The length of your bungee cord is 45.0 m. Freefall acceleration on Jupiter is 23.1 m/s2. What is the ratio of your speed on Jupiter to your speed on Earth when you have dropped 45.0 m? Ignore the effects of air resistance and assume that you start at rest.

To determine freefall acceleration on a moon with no atmosphere, you drop your handkerchief off the roof of a baseball stadium there. The roof is 113 meters tall. The handkerchief reaches the ground in 18.2 seconds. What is freefall acceleration on this moon? (State the result as a positive quantity.)

On a planet that has no atmosphere, a rocket 15.8 m tall is resting on its launch pad. Freefall acceleration on the planet is 4.45 m/s2. A ball is dropped from the top of the rocket with zero initial velocity. (a) How long does it take to reach the launch pad? (b) What is the speed of the ball just before it reaches the ground?

A croissant is dropped from the top of the Eiffel Tower. The height of the tower is 300.5 meters (ignoring the antenna, and this figure changes slightly with temperature). Ignoring air resistance, at what speed will the croissant be traveling when it hits the ground?