Question

if you observe that an object is accelerating, what should you conclude?
it must be changing direction. acceleration is a vector and vectors have both magnitude and direction. thus if an object is accelerating it must be changing direction.
it must be speeding up. if an object is accelerating that means it is speeding up.
a net force is acting on it. only forces cause acceleration. as such, if an object is accelerating it must be because a net force is acting on it.
it must be in free fall.
the forces acting on the object must be greater than the forces the object is exerting.
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1. -/1 points

which of the following are true according to newtons 2nd law? choose all that apply.
if you apply the same force to 2 objects, the one with less mass will have a greater acceleration.
if you apply the same force to 2 objects, the one with more mass will have a greater acceleration.
the larger the net force on an object is, the smaller the acceleration.
the larger the net force on an object is, the larger the acceleration.
if two objects have the same acceleration, the one with more mass will have a larger net force exerted on it.
if two objects have the same acceleration, the one with less mass will have a larger net force exerted on it.
if the acceleration is zero, then the net force is zero.

Explanation:

• First question:
• Acceleration is a vector, but an object can accelerate by changing speed (not just direction). So, the statement "It must be changing direction" is wrong.
• An object can accelerate by slowing down (negative acceleration), so "It must be speeding up" is wrong.
• According to Newton's second law \(F = ma\), if \(a

eq0\), then \(F
eq0\). So, if an object is accelerating, a net force is acting on it.

• Free - fall is a special case of acceleration (under gravity), but acceleration is not only in free - fall. So, "It must be in free fall" is wrong.
• Forces are in pairs (Newton's third law \(F_{action}=-F_{reaction}\)), and the forces acting on the object and the forces the object is exerting are action - reaction pairs. So, "The forces acting on the object must be greater than the forces the object is exerting" is wrong.
• Second question:
• Newton's second law is \(F = ma\), or \(a=\frac{F}{m}\). When \(F\) is the same, \(a\propto\frac{1}{m}\). So, if you apply the same force to 2 objects, the one with less mass will have a greater acceleration.
• Since \(a=\frac{F}{m}\), when \(F\) is the same, the one with more mass will have a smaller acceleration. So, the statement "If you apply the same force to 2 objects, the one with more mass will have a greater acceleration" is wrong.
• From \(a = \frac{F}{m}\), when \(m\) is constant, \(a\propto F\). So, the larger the net force on an object is, the larger the acceleration. The statement "The larger the net force on an object is, the smaller the acceleration" is wrong.
• As \(a=\frac{F}{m}\) (for constant \(m\)), the larger the net force on an object is, the larger the acceleration.
• From \(F = ma\), if \(a\) is the same, \(F\propto m\). So, if two objects have the same acceleration, the one with more mass will have a larger net force exerted on it.
• Since \(F = ma\), if \(a\) is the same, the one with less mass will have a smaller net force. So, the statement "If two objects have the same acceleration, the one with less mass will have a larger net force exerted on it" is wrong.
• If \(a = 0\), then from \(F=ma\), \(F = 0\).

Answer:

• First question: A net force is acting on it.
• Second question:
• If you apply the same force to 2 objects, the one with less mass will have a greater acceleration.
• The larger the net force on an object is, the larger the acceleration.
• If two objects have the same acceleration, the one with more mass will have a larger net force exerted on it.
• If the acceleration is zero, then the net force is zero.