physics exam chapter 4

an object is at rest on an incline. the component of gravity acting downward and along the incline on the object is described as Fg,x= +8.0 N. which axis is pointing up the incline?

-x axis

2 books are lying next to each other on a table. the force due to gravity on the first book is 9N and on the second is 13N. the gravitational force on the table is 125N. the floor supports the table with an upward force of 147N. in a free body diagram of the table, how many contact forces and field forces should be present?

3,1

a force of 5 N and 15 N acting on an object can produce the following net forces except...

5 N

during a three-part circus stunt, a clown holds a ball. the clown then tosses the ball up. after releasing the ball,it is caught a few moments later from above by a clown on a trapeze. which set of data could represent the normal force exerted by he ground on the first clown during the stunt? the force due to gravity on the clown is 680 N and that on the ball is 20N.

700 N, 705 N, 680 N

which is true of inertia? I. it's described in Newton's first law II. its a property of motion III. its measured by weight

I. its described in Newton's law

in action-reaction pair, the action force and the reaction force...

act on 2 different objects

how does action-reaction pairs keep a book sitting on a table in equilibrium

earth creates a downward force on the book (gravity). the book also creates a downward force on the table (gravity). the table exerts a force upward. because the book has both a downward and upward force, the net force on the book is zero and it is in equilibrium

an action exerted on an obejct which may change the object's state of rest or motion is

force

2 dogs are tugging on a toy. one pulls with a horizontal force of 14N due north and the other pulls east with a horizontal force. what is the direction of the net external force on the toy?

northwest (aka kanye's baby)

a batter strikes a ball with a bat. what is the action-reaction pair and what are the forces exerted by each

the batter exerts a force on the bat; the bat exerts a force on the batter

which of the following statements describe free-body diagrams? I. force diagrams show force vectors as arrows II. forces exerted on the object are represented III. forces exerted by the object are representedI

I and II

a truck and a ca uniformly accelerate from rest to a velocity of 3.0 m/s in equal time intervals. the truck is 10 times as massive as the car. which of the following is correct? I. the acceleration of the truck is 1/10 that of the car II. the truck travels 1/10 the distance of the car III. the force on the truck is 10 times the force on the car

III

in which situation is the net force acting on a car zero? I. the car increases speed and changes direction II. the car increase speed but doesn't change in direction III. the car maintains its speed but changes direction IV. the car maintains both its speed and direction

IV

a force unit is defined as the product of a mass unit and a unit of...

acceleration

which are true about field forces? I. field forces can be exerted by objects in physical contact II. field forces can be exerted by objects not in contact III. there are four fundamental field forces

all of the above

which describe inertia? I. a stationary object tends to resist being moved II. a moving object tends to resist a change in speed III. a moving object tends to resist a change in direction

all of the above

which of the following statements describe force diagrams? I. force diagrams show force vectors as arrows II. forces exerted on the object are represented III. forces exerted by the object are representedI

all of the above

which statements describe an object in equilibrium? I. the object is at rest II. the object is moving at constant velocity III. the net external force on the object is zero

all of the above

two forces act on an object. the magnitude of the net force acting on the object...

cannot be determine form the given info

a single force acting on an obejct is represented in a free-body diagram of the object by the following force vector: (up arrow). which of the following force vectors represents a single force acting on the object that will bring the object into equilibrium?

downward arrow

the gravitational force exerted on an object would most likely be represented by which force vector? (direction)

downwards (or south)

in interaction of action-reaction pairs involving earth and everyday objects, the effect on earth's motion is often negligible because..

earth has great inertia

a student holds a 6N block of wood from a spring balance in an express elevator that maintains constant velocity traveling between floors. a spring scale reading of 5.9 N indicates that the elevator is...

ending an ascending trip

units that measure weight are units of

force

the change in the horizontal velocity of a 12-kg scooter is +0.5m/s. what is the horizontal force acting on it?

greater than 0 N

while sitting in a chair with the back incline at an angle of 10° from the vertical, you tuck a pillow between your head and the chair. then you lower the chair back to 40° and doze off with the pillows in place. how has the net force on the pillow changed?

the net force hasnt changed because it is at rest