2. 1D Motion / Kinematics

Suppose 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)?

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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?

A lunar lander is making its descent to Moon Base I (Fig. E$2.40$). 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.

A 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. Would the rocket operate in outer space where there is no atmosphere? If so, how would you steer it? Could you brake it?

A 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. What is the magnitude of the brick's velocity just before it reaches the ground?

A large boulder is ejected vertically upward from a volcano with an initial speed of $40.0$ m/s. Ignore air resistance. What are the magnitude and direction of the acceleration while the boulder is (i) moving upward? (ii) Moving downward? (iii) At the highest point?

A large boulder is ejected vertically upward from a volcano with an initial speed of $40.0$ m/s. Ignore air resistance. At what time is it moving at $20.0$ m/s downward?

A 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. What is the speed of the rock just before it hits the street?

A large boulder is ejected vertically upward from a volcano with an initial speed of $40.0$ m/s. Ignore air resistance. When is the displacement of the boulder from its initial position zero?

When jumping, a flea accelerates at an astounding 1000 m/s², 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?

A rocket in deep space has an empty mass of 150 kg and exhausts the hot gases of burned fuel at 2500m/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?

As 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?

Figure 2–42 shows the velocity of a train as a function of time. During what periods, if any, was the acceleration constant?