The inertia of a body depends on which of the following?
- A.Its velocity
- B.Its mass
- C.Its shape
- D.The force applied to it
Correct answer
Explanation
The correct answer is B, its mass. Inertia is the tendency of a body to resist any change in its state of rest or of uniform motion, and the heavier the body the harder it is to start or to stop. For this reason mass is described as the measure of inertia.
Option A, velocity, does not alter inertia: a stationary truck and a moving truck of the same mass are equally hard to accelerate. Option C, shape, changes air resistance and the distribution of matter but not the inertia associated with straight line motion. Option D, the applied force, decides the acceleration produced, not the inertia the body already possesses. A useful everyday comparison is that a loaded truck is much harder to push into motion, and much harder to bring to a halt, than a bicycle of the same make of wheel.
Read the full article: Motion, Force and Newton's Laws: Formulas and Facts
Practice Questions
View allNewton's first law of motion is also known by which name?
- A.Law of inertia
- B.Law of momentum
- C.Law of action and reaction
- D.Law of gravitation
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The first law states that a body continues in its state of rest or of uniform motion in a straight line unless an unbalanced external force acts on it, which is exactly the property called inertia.
Read the full explanation →Which of the following is a vector quantity?
- A.Distance
- B.Speed
- C.Displacement
- D.Time
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It is the shortest distance from the starting point to the finishing point together with the direction of that straight line, so it has both magnitude and direction and is therefore a vector.
Read the full explanation →The equation force equals mass multiplied by acceleration follows from which law of motion?
- A.First law
- B.Second law
- C.Third law
- D.Law of conservation of energy
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It states that the rate of change of momentum of a body is proportional to the applied force and takes place in the direction of the force.
Read the full explanation →The recoil of a gun when a bullet is fired is explained by the conservation of which quantity?
- A.Energy
- B.Linear momentum
- C.Mass
- D.Electric charge
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Before firing, the gun and the bullet are at rest, so the total momentum of the system is zero.
Read the full explanation →What is the SI unit of momentum?
- A.Newton
- B.Joule
- C.Kilogram metre per second
- D.Newton per second
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Momentum is the product of mass and velocity, so its unit is the unit of mass multiplied by the unit of velocity, that is kilogram multiplied by metre per second.
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