Dynamics True or False Challenge

Newton's First Law states that an object at rest will stay at rest unless acted upon by a net external force.

• An object will change its state of motion only if a force is applied in the opposite direction.

• An object at rest will eventually move on its own without any force.

• An object in motion will stay in motion unless acted upon by a net external force.

• An object at rest will stay at rest unless acted upon by a net external force.

Friction always acts in the direction of motion.

• Friction acts only when there is no motion.

• Friction always opposes motion.

• False

• Friction can act in multiple directions.

Newton's Second Law can be expressed as F=ma, where F is force, m is mass, and a is acceleration.

• F=ma

• F=m/a

• F=ma^2

• F=mv

The coefficient of friction is a measure of how much frictional force exists between two surfaces.

• The coefficient of friction only applies to solid surfaces and not liquids.

• The coefficient of friction is a constant value that does not change with surface conditions.

• The coefficient of friction is a measure of the weight of an object.

• The coefficient of friction is a numerical value that represents the frictional force between two surfaces.

In circular motion, the acceleration is directed towards the center of the circle.

• Tangential acceleration is directed along the circumference of the circle.

• Centripetal acceleration is directed towards the center of the circle.

• Linear acceleration is constant in circular motion.

• Centrifugal acceleration is directed away from the center of the circle.

An object moving in a straight line will continue to do so unless a force causes it to change direction.

• An object will stop moving if no force is applied.

• This statement reflects Newton's first law of motion.

• An object will change direction only if it is at rest.

• An object in motion will eventually come to a stop without any force.

Static friction is always greater than kinetic friction for the same surfaces.

• Static friction and kinetic friction are equal for the same surfaces.

• Kinetic friction is greater than static friction for rough surfaces.

• True

• Static friction is always less than kinetic friction for the same surfaces.

Centripetal force is required to keep an object moving in a circular path.

• Centrifugal force is required to keep an object moving in a straight line.

• Centripetal force acts outward on an object in circular motion.

• Centripetal force is only needed for objects at rest.

• Centripetal force is required to keep an object moving in a circular path.

The acceleration due to gravity is approximately 9.81 m/s² on the surface of the Earth.

• 9.81 m/s²

• 9.0 m/s²

• 10.5 m/s²

• 9.81 m/s

An object in free fall experiences no frictional forces.

• False

• True

• Only in a vacuum

• Friction increases during free fall