2 Force Dynamics Intro

A moving object experiences equal but opposite forces. This means the object

• must come to rest since the forces are equal and opposite.

• must be at constant speed since the forces are equal and opposite.

• must be accelerating since the forces are equal and opposite.

• must be changing direction since the forces are equal and opposite.

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You are a passenger in a car and without increasing or decreasing its speed, the car makes a sharp left turn. You find yourself colliding with the right-hand door. Which is the correct analysis of the situation?

• Before and after the collision, there is a rightward force pushing you into the door.

• Starting at the time of collision, the door exerts a leftward force on you.

• both of the above

• neither of the above

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in the absence of a external force a moving object will

• stop immediately

• slow down and eventually come to a stop

• go faster and faster

• move with constant velocity

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when the rocket engines on a spacecraft are suddenly turned off the starship will

• stop immediately

• slow down and eventually come to a stop

• go faster and faster to infinity and beyond

• cruise with constant velocity through space

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when you sit on a chair the net external force on you is

• zero

• up

• down

• depends on your weight

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A star ship moves through empty space in a straight line at constant speed. It is far grom the gravitational effect of any start or planet. Under these circumstances the force that must be applied to maintain its motion is

• equal to its weight

• equal to its mass

• depends on how fast its going

• zero

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You are standing in a moving bus facing forward blindfolded when you suddenly fall forward (no I don,t know why you'd be blindfolded on a bus). You can infer from this that the bus

• increased velocity

• decreased velocity

• maintained constant speed but turned right

• maintained constant speed but turned left

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You are standing in a moving bus facing forward blindfolded when you suddenly fall forward (no I don,t know why you'd be blindfolded on a bus). What caused you to move forward

• gravity pulling you forward

• normal force due to your contact with the floor of the bus

• frictional force due to your contact with the floor of the bus

• no force caused you to move forward just your motion

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Which law of motion explains why you should buckle up in a car?

• An object at rest tends to stay at rest, and an object in motion tends to stay in motion, with the same direction and speed. Motion (or lack of motion) cannot change without an unbalanced force acting.

• The acceleration of an object produced by a net (total) applied force is directly related to the magnitude of the force, the same direction as the force, and inversely related to the mass of the object

• For every action (force) there is an equal and opposite reaction (force).

• Every particle attracts every other particle in the universe with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers

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What is inertia?

• the resistance of an object to change its motion

• the increase or decrease in the velocity of an object

• the amount of matter that makes up an object

• kind of like an intestinal hernia but smaller

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