Conceptual Physics Ch 2

Equilibrium occurs when

All the forces acting on an object are balanced. The sum of the +x forces on an object equals the some of the -x forces. The net force on the object is zero. The sum of the upward forces equals the sum of the downward forces.

6) A girl whose weight is 500N hangs from the middle of a bar supported by two vertical strands of rope. What is the tension in each strand? A) 0N B) 250N C) 500N D) 750N E) 1000N

B) 250N

A 15-N force and a 45-N force act on an object in opposite directions. What is the net force on the object? A) 15N B) 30N C) 45N D) 60N E) None of the above

B) 30N

What is the minimum resultant possible when adding a 5-N force to an 8-N force? A) 5N B) 3N C) 8N D) 13N E) 40N

B) 3N

What is needed to describe a vector quantity?

Both magnitude and direction

A 100-N lantern is suspended by a pair of ropes with 120 degrees between them (each 60 degrees from the vertical). The tension in each of rope is A) Less than 100N B) More than 100N C) 100N

C) 100N

What is the maximum resultant possible when adding a 2-N force to an 8-N force? A) 2N B) 6N C) 8N D) 10N E) 16N

D) 10N

A 5-N force and a 30-N force act in the same direction on an object. What is the net force on the object? A) 5N B) 25N C) 30N D) 35N E) None of the above

D) 35N

In order to find the components of a vector, you should

Draw the vector with the correct magnitude and orientation. Measure the sides of the rectangle. Draw a rectangle so that the vector is diagonal

(T/F)A quantity that has both magnitude and direction is calleda scarlar quanity

False

(T/F)A quantity that has only magnitude is called a vector quantity

False

(T/F)A single vector can be replaced by two vectors in the x- and y-directions that are at right angles to each other. These two x and y vectors are called resultants of the original vector

False

(T/F)Mass is a vector quantity

False

(T/F)Objects moving at aconstant speed in a straight-line path are said to be in static equilibrium

False

A clothesline is stretched between two trees. A tire hangs in the middle of the line and the two halves of the line make equal angles with the horizontal. The tension in the line is

Is more than the half the tire's weight

You are helping your aunt move a piano on wheels from one room to another. When you push the piano horizontally, it moves at a constant speed. What can you say about the piano?

It is in dynamic equilibrium

A barge is being pulled along a canal by two ropes that make equal angles with the direction in which the barge points. Assuming the two pulls on the barge are equal, in what direction does the barge move?

It moves straight ahead. It moves in the direction of the resultant force on it

A scalar quantity has

Only magnitude

The weight of a person can be represented by a vector that acts

Straight down, even if the person is standing on a hill

(T/F)An object in static equilibrium is in a state of no moiton

True

(T/F)Any vector can be represented by two other vectors are at right angels to each other.

True

What would be the safest way to put up a clothesline?

With some slack in the line