9TH GRADE PRACTICE
Physics Problems: Curvilinear movement and balance, Grade 9
Centripetal force, satellites and stability of bodies.
Here the conditions and analysis of the solution can be read without an account. In the simulator, you need to collect the same analyzes yourself: “Given,” formulas, order of steps and answer.
Problem statements
The answer options are there to check against, and the walkthrough opens under each problem.
Problem #16
Circular dynamics and satellitesEvaluate the statement: This is the name for the resultant force directed towards the center and creating centripetal acceleration.
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This is not a new special force: its role can be played by gravity, tension, friction, or the sum of them.
Answer
Problem #17
Circular dynamics and satellitesEvaluate the statement: the concept “Artificial satellite” means: The minimum speed of a circular orbit near the surface of the planet without taking into account the atmosphere and rotation.
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The satellite is in a long free fall and constantly misses the surface due to horizontal speed.
Answer
Problem #18
GravityEstimate the first escape velocity of the Earth at g = 9.8 m/s² and a radius of 6.4·10⁶ m.
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Answer
Problem #19
Balance and center of gravityEvaluate the statement: The point of application of the resultant forces of gravity acting on parts of the body in a uniform field.
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Its position is found by suspension or by symmetry, and in a hollow body the point may be outside the substance.
Answer
Problem #20
Balance and center of gravityEvaluate the statement: the concept of “Equilibrium conditions” means: Equilibrium is stable if a small deviation causes an impact that returns the body to its original position.
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The first condition excludes translational acceleration, the second - angular acceleration.
Answer
Problem #21
StaticsA force of 80 N acts on a 0.3 m arm. What force on the opposite 0.6 m arm can balance the lever?
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Answer
The theory behind these problems
Work through the topic if a problem will not give in.
Formulas by topic
Look up symbols and units of measurement in the reference.