Q. A mass m is attached to a string and is whirled in a horizontal circle. If the radius of the circle is halved, what happens to the tension in the string if the speed remains constant?
A.
It doubles
B.
It remains the same
C.
It halves
D.
It quadruples
Solution
Tension T = mv²/r. If r is halved, T doubles for constant speed.
Q. A mass m is attached to a string and is whirled in a vertical circle. At the highest point of the circle, what is the condition for the mass to just complete the circular motion?
A.
Tension = 0
B.
Tension = mg
C.
Tension = 2mg
D.
Tension = mg/2
Solution
At the highest point, the centripetal force is provided by the weight of the mass, so T + mg = mv²/r. For T = 0, mg = mv²/r.
Q. A mass m is attached to a string and is whirled in a vertical circle. At the highest point of the circle, what is the minimum speed required to keep the mass in circular motion?
A.
√(g*r)
B.
g*r
C.
2g*r
D.
g/2
Solution
At the highest point, the centripetal force is provided by the weight. Minimum speed = √(g*r).
Q. A mass m is attached to a string and is whirled in a vertical circle. At the highest point of the circle, the tension in the string is T. What is the expression for T?
A.
T = mg
B.
T = mg - mv²/r
C.
T = mg + mv²/r
D.
T = mv²/r
Solution
At the highest point, T + mg = mv²/r, thus T = mg - mv²/r.
Q. A mass m is attached to a string and is whirled in a vertical circle. At the top of the circle, the tension in the string is T. What is the expression for the tension at the bottom of the circle?
Q. A mass m is attached to a string of length L and is swung in a vertical circle. At the highest point of the circle, what is the minimum speed required to keep the mass in circular motion?
A.
√(gL)
B.
√(2gL)
C.
gL
D.
2gL
Solution
At the highest point, the centripetal force must equal the weight: mv²/L = mg, thus v = √(gL).
Q. A particle moves in a circular path of radius r with a constant angular acceleration α. What is the expression for the angular displacement θ after time t?
A.
θ = αt²
B.
θ = 0.5αt²
C.
θ = αt
D.
θ = 0.5αt
Solution
Angular displacement θ = 0.5αt² for constant angular acceleration.
Q. A person pushes a box with a force of 30 N, but the box does not move. If the coefficient of static friction is 0.6, what is the maximum static friction force?
A.
18 N
B.
30 N
C.
36 N
D.
60 N
Solution
The maximum static friction force is equal to the applied force when the box does not move, which is 30 N.
Q. A satellite is in a circular orbit around the Earth. If the radius of the orbit is doubled, what happens to the gravitational force acting on the satellite?
A.
It doubles
B.
It halves
C.
It becomes four times
D.
It becomes one-fourth
Solution
Gravitational force ∝ 1/r². If radius is doubled, force becomes 1/(2²) = 1/4.
Q. A satellite is in a circular orbit around the Earth. If the radius of the orbit is 7000 km and the gravitational acceleration is 9.8 m/s², what is the speed of the satellite?
Q. A satellite is in a circular orbit around the Earth. If the radius of the orbit is 7000 km and the speed of the satellite is 7.9 km/s, what is the centripetal acceleration?
Q. A stone is tied to a string and swung in a vertical circle. At the highest point, the tension in the string is 5 N and the weight of the stone is 10 N. What is the speed of the stone at the highest point if the radius of the circle is 2 m?
A.
2 m/s
B.
3 m/s
C.
4 m/s
D.
5 m/s
Solution
At the highest point, T + mg = mv²/r. 5 + 10 = (m*v²)/2. Solving gives v = 4 m/s.
The "Laws of Motion" are fundamental principles that govern the movement of objects and are crucial for students preparing for various exams. Understanding these laws not only enhances conceptual clarity but also boosts your performance in objective questions and MCQs. Practicing Laws of Motion MCQ questions helps you identify important questions and solidify your exam preparation, ensuring you are well-equipped to tackle any challenge that comes your way.
What You Will Practise Here
Newton's Three Laws of Motion: Definitions and applications
Key concepts of inertia, force, and mass
Formulas related to motion, including F=ma
Understanding friction and its effects on motion
Diagrams illustrating motion and forces
Real-life applications of Laws of Motion
Common numerical problems and their solutions
Exam Relevance
The Laws of Motion are a significant part of the syllabus for CBSE, State Boards, NEET, and JEE examinations. Questions related to this topic often appear in various formats, including direct application of formulas, conceptual understanding, and problem-solving scenarios. Students can expect to encounter both theoretical questions and numerical problems, making it essential to be well-prepared with practice questions.
Common Mistakes Students Make
Confusing the concepts of mass and weight
Misapplying Newton's laws in different scenarios
Overlooking the role of friction in motion problems
Ignoring units and dimensions in calculations
FAQs
Question: What are Newton's three laws of motion? Answer: Newton's three laws of motion describe the relationship between the motion of an object and the forces acting on it. They are: 1) An object at rest stays at rest, and an object in motion stays in motion unless acted upon by a net external force. 2) The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. 3) For every action, there is an equal and opposite reaction.
Question: How can I improve my understanding of Laws of Motion for exams? Answer: Regular practice of MCQs and objective questions, along with a thorough review of concepts and formulas, will significantly enhance your understanding and retention of the Laws of Motion.
Don't miss the chance to excel! Start solving practice MCQs on the Laws of Motion today and test your understanding to achieve your academic goals.
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