Which statements correctly describe a system of two people on in-line skates, initially at rest until one person pushes against the other?Multiple select question.The total momentum after the push will be less than zero.The total momentum after the push is zero.The total momentum after the push will be greater than zero.The total momentum before the push is zero.
Question
Which statements correctly describe a system of two people on in-line skates, initially at rest until one person pushes against the other?Multiple select question.The total momentum after the push will be less than zero.The total momentum after the push is zero.The total momentum after the push will be greater than zero.The total momentum before the push is zero.
Solution
The correct statements are:
- The total momentum after the push is zero.
- The total momentum before the push is zero.
Here's why:
Momentum is a vector quantity, meaning it has both magnitude (amount) and direction. The total momentum of a system is the vector sum of the momenta of all the objects in the system.
Before the push, both people are at rest, so their individual momenta are zero. Therefore, the total momentum of the system is zero.
After the push, one person moves in one direction and the other person moves in the opposite direction. The magnitude of the momentum of each person is equal (because they have equal mass and opposite velocities), but the directions are opposite. Therefore, when you add these two momenta together, they cancel each other out, and the total momentum of the system remains zero.
This is an example of the conservation of momentum, which states that the total momentum of a closed system is constant if no external forces are acting on it. In this case, the two people and their skates can be considered a closed system, and the push is an internal force.
Similar Questions
Multiple Select QuestionSelect all that applyWhich statements correctly describe a system of two people on in-line skates, initially at rest until one person pushes against the other?Multiple select question.The total momentum after the push is zero.The total momentum before the push is zero.The total momentum after the push will be greater than zero.The total momentum after the push will be less than zero.
Tom is teaching Jenny how to ice skate. Both skaters, who are about the same size, are on the ice and wearing their skates. To help Jenny get started, Tom gives her a gentle push from behind. Which of the following best describes what will happen next? A. Jenny will not move, and Tom will move backward. B. Jenny will move backward, and Tom will move forward. C. Jenny will move forward, and Tom will not move. D. Jenny will move forward, and Tom will move backward.
If you could skate on a perfectly smooth, frictionless surface (like ice!), what would happen when you push yourself once?a) You would immediately stopb) You would slow down due to air resistancec) You would keep moving at the same speed foreverd) You would need to keep pushing to stay moving
Two skaters, each of mass 35 kg, approach each other along parallel paths separated by 3.6 m. They have equal and opposite velocities of 1.4 m/s. The first skater carries one end of a long pole with negligible mass, and the second skater grabs the other end of it as she passes. See Fig. 12-42. Assume frictionless ice.Figure 12-42(a) Describe quantitatively the motion of the skaters after they have become connected by the pole. m (radius) rad/s (angular speed)(b) By pulling on the pole, the skaters reduce their separation to 1.0 m. What is their angular speed then? rad/s(c) Calculate the kinetic energy of the system in (a) and (b). J (energy for system a) J (energy for system b)
Two skaters, each of mass 35 kg, approach each other along parallel paths separated by 3.6 m. They have equal and opposite velocities of 1.4 m/s. The first skater carries one end of a long pole with negligible mass, and the second skater grabs the other end of it as she passes. See Fig. 12-42. Assume frictionless ice.Figure 12-42(a) Describe quantitatively the motion of the skaters after they have become connected by the pole.1.8 1.8 m (radius)0.78 0.778 rad/s (angular speed)(b) By pulling on the pole, the skaters reduce their separation to 1.0 m. What is their angular speed then?10.08 10.1 rad/s(c) Calculate the kinetic energy of the system in (a) and (b).69.3 68.6 J (energy for system a)889.056 889 J (energy for system b)(d) What is the source of the added kinetic energy?
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