physics : class11 Conservation of Angular Momentum : Second Law of Kepler : Gravitation MCQ Questions and Answers
Practice important
Conservation of Angular Momentum
MCQ questions and answers.
Page 1
of
1
|
10
MCQ Questions
1. According to the conservation of angular momentum, what remains constant for a planet moving around the Sun when no external torque acts on it?
A.
Its angular momentum
B.
Its linear speed
C.
Its distance from the Sun
D.
Its kinetic energy
Correct Answer:
Its angular momentum
Explanation:
When no external torque acts on the planet, its angular momentum about the Sun remains conserved.
2. A planet moves closer to the Sun in its elliptical orbit. What happens to its orbital speed due to conservation of angular momentum?
A.
It decreases
B.
It increases
C.
It becomes zero
D.
It remains exactly constant
Correct Answer:
It increases
Explanation:
Angular momentum is conserved, so the planet moves faster when its distance from the Sun decreases.
3. The conservation of angular momentum in planetary motion leads directly to which result?
A.
Equal areas are swept out in equal intervals of time
B.
Equal distances are covered in equal intervals of time
C.
The planet moves in a circular orbit only
D.
The planet's speed is always constant
Correct Answer:
Equal areas are swept out in equal intervals of time
Explanation:
Conservation of angular momentum makes the areal velocity constant, which is Kepler's second law.
4. If the distance of a planet from the Sun is doubled and its motion is perpendicular to the radius, what must happen to its speed for angular momentum to remain constant?
A.
Its speed must be doubled
B.
Its speed must be halved
C.
Its speed must remain unchanged
D.
Its speed must become four times larger
Correct Answer:
Its speed must be halved
Explanation:
For perpendicular motion, angular momentum is proportional to distance multiplied by speed. Doubling the distance requires halving the speed to conserve angular momentum.
5. At which position in an elliptical orbit is a planet generally moving fastest?
A.
At its closest point to the Sun
B.
At its farthest point from the Sun
C.
At the center of the Sun
D.
At every point with the same speed
Correct Answer:
At its closest point to the Sun
Explanation:
The planet moves fastest at its closest point because conservation of angular momentum requires greater speed when the orbital distance is smaller.
6. What is the angular momentum of a planet about the Sun proportional to when its velocity is perpendicular to its position vector?
A.
The product of its mass, distance, and speed
B.
Only its mass
C.
The sum of its distance and speed
D.
The difference between its mass and speed
Correct Answer:
The product of its mass, distance, and speed
Explanation:
For perpendicular position and velocity, angular momentum is given by mass multiplied by distance from the Sun and speed.
7. Why does a planet sweep out equal areas in equal times while orbiting the Sun?
A.
Because its angular momentum is conserved
B.
Because its distance from the Sun is constant
C.
Because its speed is constant everywhere
D.
Because the Sun exerts no force on it
Correct Answer:
Because its angular momentum is conserved
Explanation:
Conservation of angular momentum keeps the planet's areal velocity constant, producing equal areas in equal times.
8. If a planet's distance from the Sun decreases during part of its orbit, which quantity increases to conserve angular momentum?
A.
Its orbital speed
B.
Its distance from the Sun
C.
Its angular momentum
D.
The time required to sweep an area
Correct Answer:
Its orbital speed
Explanation:
As the orbital distance decreases, the planet's speed increases so that its angular momentum remains constant.
9. The areal velocity of a planet is the area swept out by the line joining the planet to the Sun per unit of what?
A.
Time
B.
Distance
C.
Mass
D.
Speed
Correct Answer:
Time
Explanation:
Areal velocity is defined as the area swept out by the radius vector per unit time, and it remains constant due to angular momentum conservation.
10. At the closest and farthest points of a planet's elliptical orbit, how are its velocity and position vectors oriented?
A.
They are perpendicular
B.
They are parallel in the same direction
C.
They are parallel in opposite directions
D.
They are always at an angle of 45 degrees
Correct Answer:
They are perpendicular
Explanation:
At the closest and farthest points, the planet's velocity is tangential to the orbit and therefore perpendicular to its position vector from the Sun.
Short Questions and Answers
Practice short questions and answers related to
Conservation of Angular Momentum
.
Short questions are currently unavailable for this page.