7TH GRADE PRACTICE
Physics Problems: Powers, Grade 7
Gravity, elasticity, weight, resultant 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 #25
Strength, heaviness and body weightEvaluate the statement: A vector physical quantity that is a measure of the interaction of bodies and can change the movement or deform the body.
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For force, the meaning, direction and point of application are important; One newton is the SI unit of force.
Answer
Problem #26
Strength, heaviness and body weightEvaluate the statement: the concept of “Gravity” means: Weight is the force of a body acting on a support or suspension, and weightlessness means the absence of such an action.
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On another planet, the same mass remains the same, but the force of gravity changes along with the acceleration of gravity.
Answer
Problem #27
GravityA mass of 4 kg is located at the surface of the Earth. Take the acceleration due to gravity to be 9.8 m/s². Find the force of gravity.
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Answer
Problem #28
Elasticity and resultantEvaluate the statement: A change in the shape or size of a body under the influence of external forces is called deformation.
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Elastic deformation disappears after the load is removed, while plastic deformation retains a noticeable residual trace.
Answer
Problem #29
Elasticity and resultantEvaluate the statement: The concept of “Hooke’s Law” means: One force replacing the combined action of several forces and causing the same change in motion.
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Stiffness shows how much force is needed for a unit elongation; beyond the elastic limit, the simple relationship breaks down.
Answer
Problem #30
Hooke's lawA spring with a stiffness of 200 N/m is stretched by 3 cm. Find the modulus of elasticity.
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Answer
Problem #31
Friction forceEvaluate the statement: The force that prevents the onset of relative sliding of contacting surfaces.
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It is static friction that allows the foot to push off the ground without slipping and keeps the object on an inclined surface.
Answer
Problem #32
Friction forceEvaluate the statement: the concept of “Rolling friction” means: A force directed against the relative sliding of surfaces and arising when they come into contact.
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Wheels reduce losses during transportation, but friction remains necessary for acceleration, braking and steering.
Answer
Problem #33
Friction forceThe box slides along the horizontal floor. The coefficient of friction is 0.2, the reaction force of the support is 50 N. Find the friction force.
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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.