Chapter 8: Problem 13
A projectile is launched into the air. Part way through its flight, it explodes. How does the explosion affect the motion of the center of mass of the projectile?
Chapter 8: Problem 13
A projectile is launched into the air. Part way through its flight, it explodes. How does the explosion affect the motion of the center of mass of the projectile?
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Get started for freeSam \((61 \mathrm{~kg})\) and Alice \((44 \mathrm{~kg})\) stand on an ice rink, providing them with a nearly frictionless surface to slide on. Sam gives Alice a push, causing her to slide away at a speed (with respect to the rink) of \(1.20 \mathrm{~m} / \mathrm{s}\). a) With what speed does Sam recoil? b) Calculate the change in the kinetic energy of the SamAlice system. c) Energy cannot be created or destroyed. What is the source of the final kinetic energy of this system?
Two objects with masses \(m_{1}\) and \(m_{2}\) are moving along the \(x\) -axis in the positive direction with speeds \(v_{1}\) and \(v_{2}\), respectively, where \(v_{1}\) is less than \(v_{2}\). The speed of the center of mass of this system of two bodies is a) less than \(v_{1}\). b) equal to \(v_{1}\). c) equal to the average of \(v_{1}\) and \(v_{2}\). d) greater than \(v_{1}\) and less than \(v_{2}\). e) greater than \(v_{2}\).
A spacecraft engine creates \(53.2 \mathrm{MN}\) of thrust with a propellant velocity of \(4.78 \mathrm{~km} / \mathrm{s}\). a) Find the rate \((d m / d t)\) at which the propellant is expelled. b) If the initial mass is \(2.12 \cdot 10^{6} \mathrm{~kg}\) and the final mass is \(7.04 \cdot 10^{4} \mathrm{~kg},\) find the final speed of the spacecraft (assume the initial speed is zero and any gravitational fields are small enough to be ignored). c) Find the average acceleration till burnout (the time at which the propellant is used up; assume the mass flow rate is constant until that time).
A \(1000 .-\mathrm{kg}\) cannon shoots a \(30.0-\mathrm{kg}\) shell at an angle of \(25.0^{\circ}\) above the horizontal and a speed of \(500 . \mathrm{m} / \mathrm{s}\). What is the recoil velocity of the cannon?
Young acrobats are standing still on a circular horizontal platform suspended at the center. The origin of the two-dimensional Cartesian coordinate system is assumed to be at the center of the platform. A 30.0 -kg acrobat is located at \((3.00 \mathrm{~m}, 4.00 \mathrm{~m})\), and a 40 - \(\mathrm{kg}\) acrobat is located at \((-2.00 \mathrm{~m}\) \(-2.00 \mathrm{~m})\). Assuming that the acrobats stand still in their positions, where must a 20.0 -kg acrobat be located so that the center of mass of the system consisting of the three acrobats is at the origin and the platform is balanced?
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