3. Check your understanding Q1. Newton\'s second law indicates that when a net f
ID: 1787994 • Letter: 3
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3. Check your understanding Q1. Newton's second law indicates that when a net force acts on an object, it must accelerate. Does it mean that when two or more forces are applied to an object simultaneously, it must accelerate? Explain. Q2. The net external force acting on an object is zero. Is it possible for the object to be traveling with a velocity that is not zero? If your answer is yes, state whether any conditions must be placed on the magnitude and direction of the velocity. If your answer is no, provide a reason for your answer Q3. All of the following, except one, cause the acceleration of an object to be reduced by a factor of two. Which one is it? Explain. a) The net force acting on an object is reduced by a factor of two. b) The net force acting on the object is doubled c) All forces acting on the object are reduced by a factor of two. d) The mass of the object is doubledExplanation / Answer
Not necessarily. If the net force (vector sum of all forces) is zero there will be no acceleration. This could happen, for example, if two equal and opposite forces are acting on a body, like in a tug of war game with two equally strong teams pulling a rope from opposite sides. In such cases there's no net motion and no acceleration. This could also happen with more than two forces even if they are unequal and acting in different directions. As long as the resultant force is zero, there will be no linear acceleration.
Yes, it is possible. According to Newton's second law, force = mass × acceleration, so if net external force is zero, the acceleration will be zero. As acceleration is nothing but rate of change of velocity, zero acceleration means certain constant non-changing velocity which could be non-zero. As the velocity is a vector quantity, both the magnitude and direction of velocity should be preserved, i.e. neither the magnitude nor the direction of velocity should change, only then can we say that velocity is constant and acceleration is zero. If either the magnitude or the direction changes during the motion, body is undergoing non-zero acceleration.
As mentioned above, Newton's second law states that
force = mass × acceleration
If the net force acting on the object is reduced by a factor of two, acceleration will also be reduced by a factor of two, as both are directly proportional.
If the net force acting on the object is doubled then acceleration will also be doubled and NOT reduced by a factor of two, again because both force and acceleration are directly proportional.
If all forces acting on an object are reduced by a factor of two, the net force acting on the object is also reduced by a factor of two, so acceleration will also be reduced by a factor of two, as both are directly proportional.
If the mass of the object if doubled, acceleration will be again reduced by factor of two, because the product of mass and acceleration, i.e. the force has not changed.
This in all cases except (b), acceleration is reduced by a factor of two. So the answer is (b).
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