Matter & Interactions 2nd ed. Practice Problems Aaron Titus | High Point University home
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 15d0001     Speed of a proton and electron interacting with a charged sphere.     15d0001 View Question | View Solution | Download pdf The charged sphere shown below has a net positive charge of 1 nC and is very massive compared to a single proton. Figure: A charged sphere. What is the speed of a proton at point 2 if it is moving to the right with a speed of at point 1? What is the speed of a proton at point 2 if it is moving to the left with a speed of at point 1? What is the speed of an electron at point 2 if it is moving to the right with a speed of at point 1?
 1540001     Final speed of a space probe with thrusters firing; application of the update form of the energy principle     1540001 View Question | View Solution | Download pdf In a 3-D computer game, a 5000-kg space probe in space (far from any significant interactions with planets or stars) has four thrusters that fire in the +x, –x, +y, and –y directions, respectively. As the space probe moves from to , there are two thrusters simultaneously firing with forces and respectively. If the initial speed of the space probe is 200 m/s, what is its final speed? State any assumptions that you make. Figure: Thrusters on a spaceship firing in the +y and – x directions, respectively.
 1550002     Kinetic energy of particles resulting from the decay of a neutron.     1550002 View Question | View Solution | Download pdf A free neutron (mass ) is highly unstable, meaning that it won't exist for very long before it decays. When it decays, it decays into a proton (mass , an electron (mass , and an antineutrino. If a neutron at rest decays, what will be the total kinetic energy of the proton, electron, and antineutrino when they are very far apart? An antineutrino has no rest energy (or actually it has negligible rest energy). Why is it impossible for all three particles to travel in the same direction after the decay?
 1550001     Change in rest energy resulting from the fusion of hydrogen into helium.     1550001 View Question | View Solution | Download pdf In one type of fusion reaction, 6 hydrogen nuclei (each nuclei is one proton) eventually, after many steps, form 1 atom of helium (2 neutrons and 2 protons) and two atoms of hydrogen. (Read more about the proton-proton cycle to learn about the process.) The mass of hydrogen is . The mass of helium is . What is the change in the rest energy of the system during this reaction?
 1570001     Work done on a springs in a piece of exercise equipment     1570001 View Question | View Solution | Download pdf The piece of exercise equipment shown below includes two handles that are on each end of two parallel springs, each with a stiffness 500 N/m. To build strength, a person holds the two handles and pulls them apart with equal magnitude forces applied in opposite directions to the handles, thus stretching the springs. Neglect the mass of the springs and assume that they are pulled horizontally. Figure: Two parallel springs between two handles that can be pulled apart. How much work must a person do to stretch the springs 5 cm? Suppose that a person is already holding the handles so that the springs are stretched 5 cm from their relaxed lengths. How much more work must the person do to stretch the springs an additional 5 cm (i.e. from 5 cm stretched to 10 cm stretched)?
 1530001     Work done on a pole vaulter during a vault     1530001 View Question | View Solution | Download pdf The path of a pole vaulter is measured using video analysis. The y vs. x graph (which shows the path) of the pole vaulter is shown below. Figure: The path of a pole vaulter. The mass of the vaulter is 70.0 kg. He plants the pole when he is at the location , and the pole starts to bend. With the pole mostly bent, the vaulter starts his mostly upward trajectory at the location . The average force by the pole on the pole vaulter during this interval is . What is the total work done on the pole vaulter during this interval? State any assumptions that you make.
 15a0001     Initial speed of a space probe traveling from Earth to Jupiter along a ``least energy" orbit     15a0001 View Question | View Solution | Download pdf To send a probe from earth to another outer planet, it is most efficient (i.e. conserves the most fuel) to put the probe into an orbit about Sun so that when it is nearest Sun (perihelion), its path is tangent to the earth's orbit, and when it is furthest from Sun (aphelion), its path is tangent to the outer planet's orbit. Besides the fuel necessary to put the probe into orbit (i.e. escape from Earth) and to make it orbit the outer planet once it gets there, no fuel is necessary during travel from Earth to the outer planet. For this reason, the probe's orbit in this case is called a "least-energy" orbit. Suppose the probe travels from Earth to Jupiter as shown below. The radius of the Earth's nearly circular orbit is , and the radius of Jupiter's nearly circular orbit is . Figure: The path of a probe leaving Earth at perihelion and arriving at Jupiter at aphelion. If the probe's speed at aphelion should be the same as the speed of Jupiter ( ), what should be the probe's speed at perihelion, when it leaves Earth with its thrusters turned off? Neglect interactions of the probe with Earth and Jupiter, and assume that the probe's motion is completely determined by its interaction with Sun.
 15a0002     The work needed to launch the Hubble Space Telescope into orbit.     15a0002 View Question | View Solution | Download pdf The Hubble Space Telescope (HST or "the Hubble") has a mass of about 11,100 kg and is in a nearly circular orbit of altitude 560 km. Use the momentum principle to calculate the speed of the HST. What is the period of its orbit? What is the work needed to put the HST into orbit, starting at the surface of Earth?
 15c0001     Speed of a roller coaster at the top of the loop.     15c0001 View Question | View Solution | Download pdf A roller coaster has a speed of 2.0 m/s at the top of a 60.0-m tall hill as shown below. If friction is negligible, what is the speed of the roller coaster at the top of the loop that has a radius of 20.0 m? Figure: A roller coaster.
 15b0001     Launch speed of rocket from Moon     15b0001 View Question | View Solution | Download pdf Moon has a mass of and a radius of . Moon has no atmosphere, so there is no air resistance. Suppose that a manned lunar rocket on the surface of Moon must launch so that when it is very far from Moon, it has a speed of 1500 m/s. What is the required launch speed? (Treat the rocket as a particle with constant mass.)

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