9TH GRADE PRACTICE
Physics Problems: Newton's laws, Grade 9
Inertial systems, forces, gravity, weight and friction.
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 #10
Newton's three lawsEvaluate the statement: The acceleration of a body is determined by the vector sum of forces and is inversely proportional to the mass.
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First, all forces are added as vectors, then each projection of the resultant is associated with the corresponding acceleration.
Answer
Problem #11
Newton's three lawsEvaluate the statement: the concept of “Inertial frame of reference” means: Two bodies act on each other with forces equal in magnitude, opposite and applied to different bodies.
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A system moving uniformly relative to an inertial system is also inertial in school mechanics.
Answer
Problem #12
Newton's lawsA body of mass 3 kg is acted upon by a constant resultant force of 12 N. Find the acceleration.
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Answer
Problem #13
Gravity, elasticity, weight and frictionEvaluate the statement: Any two bodies attract with a force depending on their masses and the distance between them.
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For spheres, the distance is taken between centers; acceleration g depends on the mass and radius of the celestial body, so it is different on other planets.
Answer
Problem #14
Gravity, elasticity, weight and frictionEvaluate the statement: The concept of "Weight, overload and weightlessness" means: Elasticity is associated with deformation and tends to restore shape, and friction prevents the relative movement of surfaces.
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Weightlessness does not mean the disappearance of gravity; the body and the support simply fall with the same acceleration.
Answer
Problem #15
Elastic forceA spring with a stiffness of 250 N/m lengthens by 4 cm. Find the modulus of the elastic force.
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Answer
The theory behind these problems
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Formulas by topic
Look up symbols and units of measurement in the reference.