06:04Physics, Kinematics, Free Fall - Solving for Time to Fall from Known HeightStep by Step Science811views
05:58Physics, Kinematics, Free Fall - Height Reached from Known Initial VelocityStep by Step Science385views1rank
Multiple ChoiceA rock is thrown vertically upward with a speed of 27.0 m/s from the roof of a 31.0-m-tall building. The rock doesn't hit the building on its way back down and lands in the street below. (a) What is the speed of the rock just before it hits the street? (b) How much time elapses from when the rock is thrown until it hits the street?4605views25rank5comments
Multiple ChoiceA student throws a set of keys vertically upward to her sorority sister who is in a window 14.00 m above. The second student catches the keys 1.50 s later. (a) With what initial velocity were the keys thrown? (b) What was the velocity of the keys just before they were caught?2211views34rank9comments
Multiple ChoiceA steel ball is dropped onto a thick piece of foam. The ball is released 2.0 meters above the foam. The foam compresses 3.0cm as the ball comes to rest. How fast is the ball moving when it first hits the foam? Ignore air resistance.703views
Multiple ChoiceA steel ball is dropped onto a thick piece of foam. The ball is released 2.5 meters above the foam. The foam compresses 3.0cm as the ball comes to rest. What is the magnitude of the ball's acceleration as it comes to rest on the foam? Ignore air resistance.765views
Multiple ChoiceA toy rocket starts on the ground at rest. Its engine burns for 3.0s giving it a constant acceleration of 4.0m/s2. What is the maximum height achieved by the rocket?1222views2comments
Textbook QuestionA hotel elevator ascends 200 m with a maximum speed of 5.0 m/s. Its acceleration and deceleration both have a magnitude of 1.0 m/s². b. How long does it take to make the complete trip from bottom to top?461views
Textbook QuestionWhen jumping, a flea accelerates at an astounding 1000 m/s^2, but over only the very short distance of 0.50 mm. If a flea jumps straight up, and if air resistance is neglected (a rather poor approximation in this situation), how high does the flea go?2475views1rank1comments
Textbook QuestionA 200 kg weather rocket is loaded with 100 kg of fuel and fired straight up. It accelerates upward at 30 m/s² for 30 s, then runs out of fuel. Ignore any air resistance effects. a. What is the rocket's maximum altitude?1383views
Textbook QuestionA 1000 kg weather rocket is launched straight up. The rocket motor provides a constant acceleration for 16 s, then the motor stops. The rocket altitude 20 s after launch is 5100 m. You can ignore any effects of air resistance. What was the rocket's acceleration during the first 16 s?2105views
Textbook QuestionA rock is tossed straight up from ground level with a speed of 20 m/s. When it returns, it falls into a hole 10 m deep. (a) What is the rock's speed as it hits the bottom of the hole?2226views
Textbook QuestionA lead ball is dropped into a lake from a diving board 5.0 m above the water. After entering the water, it sinks to the bottom with a constant velocity equal to the velocity with which it hit the water. The ball reaches the bottom 3.0 s after it is released. How deep is the lake?1312views
Textbook QuestionAs a science project, you drop a watermelon off the top of the Empire State Building, 320 m above the sidewalk. It so happens that Superman flies by at the instant you release the watermelon. Superman is headed straight down with a speed of 35 m/s. How fast is the watermelon going when it passes Superman?2272views
Textbook QuestionBall bearings are made by letting spherical drops of molten metal fall inside a tall tower—called a shot tower—and solidify as they fall. (b) What is the bearing's impact velocity?433views
Textbook QuestionBall bearings are made by letting spherical drops of molten metal fall inside a tall tower—called a shot tower—and solidify as they fall. (a) If a bearing needs 4.0 s to solidify enough for impact, how high must the tower be?1199views
Textbook QuestionA rocket is launched straight up with constant acceleration. Four seconds after liftoff, a bolt falls off the side of the rocket. The bolt hits the ground 6.0 s later. What was the rocket's acceleration?1298views1rank
Textbook QuestionA hot-air balloonist, rising vertically with a constant velocity of magnitude 5.00 m/s, releases a sandbag at an instant when the balloon is 40.0 m above the ground (Fig. E2.44). After the sandbag is released, it is in free fall. (d) What is the greatest height above the ground that the sandbag reaches? 426views
Textbook QuestionA hot-air balloonist, rising vertically with a constant velocity of magnitude 5.00 m/s, releases a sandbag at an instant when the balloon is 40.0 m above the ground (Fig. E2.44). After the sandbag is released, it is in free fall. (a) Compute the position and velocity of the sandbag at 0.250 s and 1.00 s after its release. 1523views1rank
Textbook QuestionA lunar lander is making its descent to Moon Base I (Fig. E2.40). The lander descends slowly under the retro-thrust of its descent engine. The engine is cut off when the lander is 5.0 m above the surface and has a downward speed of 0.8 m/s.With the engine off, the lander is in free fall. What is the speed of the lander just before it touches the surface? The acceleration due to gravity on the moon is 1.6 m/s 1016views
Textbook QuestionYou throw a glob of putty straight up toward the ceiling, which is 3.60 m above the point where the putty leaves your hand. The initial speed of the putty as it leaves your hand is 9.50 m/s. (a) What is the speed of the putty just before it strikes the ceiling?466views
Textbook QuestionA small rock is thrown vertically upward with a speed of 22.0 m/s from the edge of the roof of a 30.0-m-tall building. The rock doesn't hit the building on its way back down and lands on the street below. Ignore air resistance. (b) How much time elapses from when the rock is thrown until it hits the street?813views1rank
Textbook QuestionA small rock is thrown vertically upward with a speed of 22.0 m/s from the edge of the roof of a 30.0-m-tall building. The rock doesn't hit the building on its way back down and lands on the street below. Ignore air resistance. (a) What is the speed of the rock just before it hits the street?538views
Textbook QuestionA 15-kg rock is dropped from rest on the earth and reaches the ground in 1.75 s. When it is dropped from the same height on Saturn's satellite Enceladus, the rock reaches the ground in 18.6 s. What is the acceleration due to gravity on Enceladus?1238views
Textbook QuestionA brick is dropped (zero initial speed) from the roof of a building. The brick strikes the ground in 1.90 s. You may ignore air resistance, so the brick is in free fall. (b) What is the magnitude of the brick's velocity just before it reaches the ground?1201views
Textbook QuestionA brick is dropped (zero initial speed) from the roof of a building. The brick strikes the ground in 1.90 s. You may ignore air resistance, so the brick is in free fall. (a) How tall, in meters, is the building?564views
Textbook QuestionA large boulder is ejected vertically upward from a volcano with an initial speed of 40.0 m/s. Ignore air resistance. (e) What are the magnitude and direction of the acceleration while the boulder is (i) moving upward? (ii) Moving downward? (iii) At the highest point?398views
Textbook QuestionA large boulder is ejected vertically upward from a volcano with an initial speed of 40.0 m/s. Ignore air resistance. (d) When is the velocity of the boulder zero?489views
Textbook QuestionA large boulder is ejected vertically upward from a volcano with an initial speed of 40.0 m/s. Ignore air resistance. (c) When is the displacement of the boulder from its initial position zero?684views
Textbook QuestionA large boulder is ejected vertically upward from a volcano with an initial speed of 40.0 m/s. Ignore air resistance. (b) At what time is it moving at 20.0 m/s downward?551views
Textbook QuestionA large boulder is ejected vertically upward from a volcano with an initial speed of 40.0 m/s. Ignore air resistance. (a) At what time after being ejected is the boulder moving at 20.0 m/s upward?943views
Textbook QuestionAn egg is thrown nearly vertically upward from a point near the cornice of a tall building. The egg just misses the cornice on the way down and passes a point 30.0 m below its starting point 5.00 s after it leaves the thrower's hand. Ignore air resistance. (d) What are the magnitude and direction of its acceleration at the highest point?452views
Textbook QuestionAn egg is thrown nearly vertically upward from a point near the cornice of a tall building. The egg just misses the cornice on the way down and passes a point 30.0 m below its starting point 5.00 s after it leaves the thrower's hand. Ignore air resistance. (c) What is the magnitude of its velocity at the highest point?1151views
Textbook QuestionAn egg is thrown nearly vertically upward from a point near the cornice of a tall building. The egg just misses the cornice on the way down and passes a point 30.0 m below its starting point 5.00 s after it leaves the thrower's hand. Ignore air resistance. (b) How high does it rise above its starting point?1596views
Textbook QuestionAn egg is thrown nearly vertically upward from a point near the cornice of a tall building. The egg just misses the cornice on the way down and passes a point 30.0 m below its starting point 5.00 s after it leaves the thrower's hand. Ignore air resistance. (a) What is the initial speed of the egg?530views
Textbook QuestionA 7500-kg rocket blasts off vertically from the launch pad with a constant upward acceleration of 2.25 m/s2 and feels no appreciable air resistance. When it has reached a height of 525 m, its engines suddenly fail; the only force acting on it is now gravity. (b) How much time will elapse after engine failure before the rocket comes crashing down to the launch pad, and how fast will it be moving just before it crashes?1634views
Textbook QuestionA 7500-kg rocket blasts off vertically from the launch pad with a constant upward acceleration of 2.25 m/s2 and feels no appreciable air resistance. When it has reached a height of 525 m, its engines suddenly fail; the only force acting on it is now gravity. (a) What is the maximum height this rocket will reach above the launch pad?583views
Textbook QuestionA tennis ball on Mars, where the acceleration due to gravity is 0.379g and air resistance is negligible, is hit directly upward and returns to the same level 8.5 s later. (b) How fast was it moving just after it was hit?632views
Textbook QuestionA tennis ball on Mars, where the acceleration due to gravity is 0.379g and air resistance is negligible, is hit directly upward and returns to the same level 8.5 s later. (a) How high above its original point did the ball go?2623views
Textbook QuestionA juggler throws a bowling pin straight up with an initial speed of 8.20 m/s. How much time elapses until the bowling pin returns to the juggler's hand?813views
Textbook Question(b) If a flea can jump straight up to a height of 0.440 m, How long is it in the air?533views
Textbook Question(a) If a flea can jump straight up to a height of 0.440 m, what is its initial speed as it leaves the ground?675views
Textbook QuestionYou throw a small rock straight up from the edge of a highway bridge that crosses a river. The rock passes you on its way down, 6.00 s after it was thrown. What is the speed of the rock just before it reaches the water 28.0 m below the point where the rock left your hand? Ignore air resistance.4968views2comments
Textbook QuestionYou throw a glob of putty straight up toward the ceiling, which is 3.60 m above the point where the putty leaves your hand. The initial speed of the putty as it leaves your hand is 9.50 m/s. (b) How much time from when it leaves your hand does it take the putty to reach the ceiling?731views
Textbook QuestionNicole throws a ball straight up. Chad watches the ball from a window 5.0 m above the point where Nicole released it. The ball passes Chad on the way up, and it has a speed of 10 m/s as it passes him on the way back down. How fast did Nicole throw the ball?586views
Textbook QuestionA typical laboratory centrifuge rotates at 4000 rpm. Test tubes have to be placed into a centrifuge very carefully because of the very large accelerations. b. For comparison, what is the magnitude of the acceleration a test tube would experience if dropped from a height of 1.0 m and stopped in a 1.0-ms-long encounter with a hard floor?357views
Textbook Questionb. The motor of a 350 g model rocket generates 9.5 N thrust. If air resistance can be neglected, what will be the rocket's speed as it reaches a height of 85 m?372views
Textbook QuestionA small rocket burns 0.0500 kg of fuel per second, ejecting it as a gas with a velocity relative to the rocket of magnitude 1600 m/s. (a) What is the thrust of the rocket?779views
Textbook QuestionA small rocket burns 0.0500 kg of fuel per second, ejecting it as a gas with a velocity relative to the rocket of magnitude 1600 m/s. (b) Would the rocket operate in outer space where there is no atmosphere? If so, how would you steer it? Could you brake it?406views
Textbook Question(I) A stone is dropped from the top of a cliff. It is seen to hit the ground below after 3.25 s. How high is the cliff?459views
Textbook Question(I) If a car rolls gently (v₀ = 0) off a vertical cliff, how long does it take it to reach 55 km/h?314views
Textbook Question(II) Figure 2–42 shows the velocity of a train as a function of time.(c) During what periods, if any, was the acceleration constant?<IMAGE>454views
Textbook Question(II) A baseball is hit almost straight up into the air with a speed of 22 m/s. Estimate(a) how high it goes, and460views
Textbook Question(II) The best rebounders in basketball have a vertical leap (that is, the vertical movement of a fixed point on their body) of about 120 cm.(b) How long are they in the air?423views
Textbook Question(II) A baseball is seen to pass upward by a window with a vertical speed of 13 m/s. If the ball was thrown by a person 18 m below on the street,(c) when was it thrown, and455views
Textbook Question(II) Roger sees water balloons fall past his window. He notices that each balloon strikes the sidewalk 0.83 s after passing his window, 15 m above the sidewalk.(b) Assuming the balloons are being released from rest, from what height are they being released?313views
Textbook Question(II) Pelicans tuck their wings and free-fall straight down when diving for fish. Suppose a pelican starts its dive from a height of 16.0 m and cannot change its path once committed. If it takes a fish 0.20 s to perform evasive action, at what minimum height must it spot the pelican to escape? Assume the fish is at the surface of the water.445views
Textbook Question(III) A falling stone takes 0.28 s to travel past a window 2.2 m tall (Fig. 2–49). From what height above the top of the window did the stone fall?<IMAGE>490views
Textbook Question(III) A toy rocket moving vertically upward passes by a 2.0-m-high window whose base is 8.0 m above the ground. The rocket takes 0.15 s to travel the 2.0 m height of the window. What was the launch speed of the rocket, and how high will it go? Assume the propellant is burned very quickly at blastoff.379views
Textbook QuestionA person jumps out a fourth-story window 18.0 m above a firefighter's safety net. The survivor stretches the net 1.0 m before coming to rest, Fig. 2–50. (a) What was the average deceleration experienced by the survivor when she was slowed to rest by the net? (b) What would you do to make it 'safer' (that is, to generate a smaller deceleration): would you stiffen or loosen the net? Explain. <IMAGE>408views
Textbook QuestionSuppose a car manufacturer tested its cars for front-end collisions by hauling them up on a crane and dropping them from a certain height. What height corresponds to a collision at(b) 35 km/h?312views
Textbook Question(II) A rocket rises vertically, from rest, with an acceleration of 3.2 m/s² until it runs out of fuel at an altitude of 725 m. After this point, its acceleration is that of gravity, downward.(c) What maximum altitude does the rocket reach?496views
Textbook Question(II) A helicopter is ascending vertically with a constant speed of 6.40 m/s. At a height of 105 m above the Earth, a package is dropped from the helicopter. How much time does it take for the package to reach the ground? [Hint: What is v₀ for the package?]455views
Textbook QuestionSuppose a 65-kg person jumps from a height of 3.0 m down to the ground.What is the speed of the person just before landing (Chapter 2)?<IMAGE>293views
Textbook QuestionTwo children are playing on two trampolines. The first child bounces up one-and-a-half times higher than the second child. The initial speed upwards of the second child is 4.0 m/s.(b) What is the initial speed of the first child?319views
Textbook QuestionA parachutist bails out of an airplane, and freely falls 75 m (ignore air friction). Then the parachute opens, and her acceleration is ― 1.5 m/s² (up). The parachutist reaches the ground with a speed of 1.5 m/s.(a) From how high did she bail out of the plane?375views
Textbook QuestionA rocket in deep space has an empty mass of 150 kg and exhausts the hot gases of burned fuel at 2500 m/s . It is loaded with 600 kg of fuel, which it burns in 30 s. What is the rocket's speed 10 s, 20 s, and 30 s after launch?351views
Textbook Questionb. A rocket with a total mass of 330,000 kg when fully loaded burns all 280,000 kg of fuel in 250 s. The engines generate 4.1 MN of thrust. What is this rocket's speed at the instant all the fuel has been burned if it is launched in deep space? If it is launched vertically from the earth?263views
Textbook QuestionBill can throw a ball vertically at a speed 1.5 times faster than Joe can. How many times higher will Bill's ball go than Joe's?581views
Textbook Question(II) For an object falling freely from rest, show that the distance traveled during each successive second increases in the ratio of successive odd integers (1, 3, 5, etc.). (This was first shown by Galileo.) See Figs. 2–27 and 2–30.232views
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