Acceleration, Forces, & Newton's Laws Review

One Newton is equal to

1 kg m/s^2

At what rate would a 10 N force accelerate a 1000 g mass?

10 m/s^2

Basking in the sun, a 1.10kg lizard lies on a flat rock tilted at an angle of 15.0 degrees with respect to the horizontal. Draw a free body diagram for this situation. Include friction. Why do we not need to consider air resistance?

25. FBD should include Fg (straight down), Fn (out of the slope), Ff (up the slope). We do not need to consider air resistance because the lizard is not moving

A man is pushing right with 50 N and friction is pushing left with 10 N, what is the net force?

40 N

This measures the rate of change in velocity.

Acceleration

State Newton's first law of motion.

An object at rest remains at rest and an object in motion continues in motion with constant velocity unless it experiences a net external force.

In the equation form of Newton's second law, EF = ma, what does EF represent?

EF is the vector sum of the external forces acting on the object.

True or False: Forces act alone.

False

Another name for a push or a pull.

Force

Cause of acceleration

Force

In a free-body diagram of an object, why are forces exerted by the object not included in the diagram?

Forces exerted by the object do not change its motion.

In a game of tug-of-war, a rope is pulled by a force of 75 N to the left and by a force of 102 N to the right. What is the magnitude and direction of the net horizontal force on the rope?

Given: F1= 102 N, to the right F2= 75 N, to the left Solution Fnet= F1+F2 Fnet= F1-F2= 102 N- 75 N= 27 N Fnet= 27 N, to the right

A wagon having a mass of 32 kg is accelerated across a level road at 0.50 m/s^2. What net force acts on the wagon horizontally?

Given: m= 33 kg a= 0.50 m/s^2 Solution: Fnetyx= EFx= max= (32 kg)(0.50m/s^2)= 16 N

What happens to air resistance when an object accelerates?

In most cases, air resistance increases with increasing speed.

What do we call the sum of the combined forces of an object?

Net force

This law states that objects resist changes in motion unless acted upon by an unbalanced force.

Newton's 1st Law

Which law explains why the dishes do not move during this magic trick?

Newton's 1st Law

Which law uses F=ma to show that acceleration depends on an object's mass and force applied?

Newton's 2nd Law

This law states that for every action, there is an equal and opposite reaction.

Newton's 3rd Law

In what unit of measurement do we express force?

Newtons

Normal force always points...

Perpendicular, away from a surface

Which statement about the acceleration of an object is correct?

The acceleration of an object is directly proportional to the net external force acting on the object and inversely proportional to the mass of the object.

What are the units of the coefficient of friction?

The coefficient of friction has no units

True of False: A force is required to change motion.

True

True or False: Acceleration can be a change in speed or direction or both.

True

True or False: While your body pushes against your chair, your chair also pushed against you.

True

Acceleration is a change in

Velocity

Which are simultaneous equal but opposite forces resulting from the interaction of two objects?

action-reaction pairs

If a nonzero net force is acting on an object, then the object is definitely

being accelerated.

What can forces do?

change an object's speed, change an object's direction, act at a distance

Which of the following forces exists between objects even in the absence of direct physical contact?

field force

Which force acts at a distance?

field, magnetism

What causes a moving object to change direction?

force

Which of the following is the tendency of an object to maintain its state of motion?

force

A free-body diagram represents all of the following except

forces exerted by the object.

Contact force?

friction

What do we call the tendency of objects to resist a change in motion?

inertia

The length of a force vector represents the

magnitude of the force.

A measure of the quantity of matter is

mass.

A crate is released on a frictionless plank inclined at angle 0 with respect to the horizontal. Which of the following relationships is true? (Assume that the x-axis is parallel to the surface of the incline.)

none of the above

Newton's third law of motion involves the interactions of

two objects and two forces.

Which type of force produces an acceleration?

unbalanced force

A change in the gravitational force acting on an object will affect the object's

weight.

The magnitude of the gravitational force acting on an object is

weight.

A car goes forward along a level road at constant velocity. The additional force needed to bring the car into equilibrium is

zero.