Newton's Laws
According to Newton’s First Law, what condition must be true for an object to maintain constant velocity?
No net external force acts on it.
What is the difference between weight and mass?
Mass is the amount of matter; weight is the gravitational force acting on that mass.
What happens to the normal force as the incline angle increases?
It decreases because less of the gravitational force acts perpendicular to the surface.
Why do passengers feel “thrown forward” when a car suddenly stops?
because of newton's 1st law (inertia)
What type of force does a spring exert when it’s stretched or compressed?
A spring force or restoring force
A car is moving at constant velocity. Is it possible for friction to be acting on the car?
Yes, friction can act but must be balanced by an equal forward driving force.
Why does a scale read less than your true weight when you’re in an elevator accelerating downward?
The normal force is reduced because the net acceleration is downward.
Why does static friction adjust itself up to a maximum value?
It resists motion by matching the applied force until it reaches its limit.
A book rests on a table. Identify Newton's 3rd law in this scenario
Book pushes on table; table pushes on book.
According to Hooke’s Law, if you double the stretch of a spring, what happens to the restoring force?
It doubles, because force is proportional to displacement
If the net force on an object doubles but its mass is halved, how does its acceleration change?
Increases by a factor of four
Two boxes are connected by a string on a frictionless surface. If you pull the first box, how do the tension forces on each box compare?
The tension is the same throughout the string (neglecting mass of string).
If the coefficient of kinetic friction doubles, what happens to the object’s acceleration down the same incline?
Acceleration decreases; frictional force doubles while gravitational component is unchanged.
Why does a lightweight car accelerate more than a heavy truck when both experience the same net force?
Acceleration is inversely proportional to mass (Newton’s Second Law).
A spring is stretched and let go, what happens to the spring force as it goes towards the equillibrium position?
It decreases
If you lean on a wall is the wall or you exerting a greater force?
trick question: they are exerting equal forces.
A block slides down an inclined plane at constant speed. What does this reveal about the relationship between gravity and friction?
The component of gravity down the slope is exactly balanced by friction.
Does the frictional force increase or decrease when an objects goes past fsmax and moves?
It decreases because kinetic friction is always less than static friction
The net centripetal force has this proportionality with the radius.
It is inversely proportional to the radius
What happens to the center of mass of a uniformly distributed system when you add a weight to the left side.
The center of mass is moved to the left
Does a car rounding a corner at a constant speed have acceleration?
yes because the direction of velocity changes
What is the source of the centripetal acceleration when a child is spinning on a merry go round?
static friction
4