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Unit Test - Chapters 3 & 6

Terms in this set (46)

a vector is a quantity that has
magnitude and direction
a scalar is a quantity that has
ONLY magnitude
when representing velocity as a vector
• the length of the arrow represents the speed
• the direction of the arrow shows the direction of motion
• the length of the arrow is drawn to a suitable scale
in order to find the components of a vector, you should
• measure the sides of the rectangle
• draw the vector with correct magnitude and orientation
• draw a rectangle so that the vector is diagonal
what is NOT be considered a projectile?
Cannonball
a. thrown through the air
b. thrown straight up
c. rolling down a slope
d. rolling off edge of cliff
C. a cannonball ROLLING down a slope
the horizontal component of a projectile's velocity is independent of
the vertical component of its velocity
TRUE or FALSE: in the absence of air friction, the vertical component of a projectile's velocity doesn't change as the projectile moves.
FALSE!!!!
TRUE or FALSE: in the absence of air friction, the horizontal component of a projectile's velocity doesn't change as the projectile moves.
TRUE!!!!
at the instant a ball is thrown horizontally with a large force, an identical ball is dropped from the same height. Which ball hits the ground first?
neither -- they both hit the ground at the same time
a ball thrown in the air will never of as far as physics would ideally predict because
air friction slows the ball
at what part of a path does a projectile have a minimum speed?
at the top of its path
a projectile launched horizontally hits the ground in 0.5 seconds. If it had been launched with a much higher speed in the same direction, it would have hit the ground (neglecting the earth's curvature and air resistance) in
0.5 seconds
a cannonball is launched horizontally from a tower. If the cannon has a barrel velocity of 100 m/s, where will the cannonball be in 1 second? (neglect air resistance)
100 m downrange
v = 100m/s
dy = 1/2gt^2 // dx = vt
100 m/s * 1 s = 100 m (= dx)
after a rock that is thrown straight up reaches the top of its path and it starting to fall back down, its acceleration is
the same as when it was at the top of its path
an airplane flying into a head wind loses ground speed, and an airplane flying with the wind gains ground speed. If an airplane flies at right angles to the wind, then ground speed is
more
Jose can jump vertically 1 meter from his skateboard when it is at rest. when the skateboard is moving horizontally, Jose can jump
no higher
which best approximates the resultant of a pair of 10-unit vectors at right angles to each other?
14 N
c = square root of 2 * 10
c = 1.414 * 10
c = 14.14 = 14 N
what is the resultant of a 4-unit vector and 3-unit vector at right angles to each other?
5 N (3, 4, 5 rule)
suppose a small plane can fly at 200 km/h relative tot he surrounding air. Suppose also that there is a 40-km/h tailwind. How fast does the plane's shadow move across the ground?
240 km/h
200 + 40 = 240 km/h
TRUE or FALSE: whenever an object exerts a force on another object, the second object exerts a force of the same magnitude, but in the opposite direction to that of the first object.
TRUE
a high school student hits a nails with a hammer. during the collision, there is a force
on the nail and also on the hammer
force always occurs
in pairs
an archer shoots an arrow. Consider the action force to be the bow string against the arrow. The reaction to this force is the
arrows's push against the bowstring
a player catches a ball. consider the action force to be the impact of the ball against the player's glove. What is the reaction to this force?
the force the glove exerts on the ball
a player hits a ball with a bat. The action force is the impact of the bat against the ball. What is the reaction of this force?
the force of the ball against the bat
as a ball falls, the action force is the pull of the earth's mass on the ball. What is the reaction to this force?
the pull of the ball's mass on the earth
a person is attracted towards the center of the earth by a 500-N gravitational force. The force with which the earth is attracted toward the person
500 N
an unfortunate bug slatters against the windshield of a moving car. Compared to the force of the car on the bug, the force of the bug on the car is
the same
an unfortunate bug splatters against the windshield of a moving car. Compared to the force of the car on the bug, the force of the bug of the car is
the same
a Mack truck (super big) and a Volkswagen (big) traveling at the same speed have a head-on collision. The vehicle to undergo the greater change in velocity will be the
Volkswagen
the earth pulls on the moon, and similarly the moon pulls on the earth. This is evidence that the
earth and moon are simply pulling on each other. and the earth's and moon's pulls comprise an action-reaction pair
a rocket is able to accelerate in the vacuum of space when it fires its engines. The force that propels the rocket in the force
of the exhaust gases on the rocket
a karate chop delivers a blow of 3000 N to a board that breaks. The force that acts on the hand during this feat
is 3000 N
F1 = F2
TRUE or FALSE: a quantity that has both magnitude and direction is called a scalar
FALSE
TRUE or FALSE: a quantity that has only magnitude is called a vector
FALSE
TRUE or FALSE: the vector sum is called the resultant
TRUE
TRUE or FALSE: the length of a vector represents its magnitude
TRUE
TRUE or FALSE: the orientation of a vector represents its magnitude
TRUE
TRUE or FALSE: when adding two vectors at right angles, the resultant of the vectors is the algebraic sum of the two vectors
FALSE
TRUE or FALSE: 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 the resultants of the original vector
FALSE
The first part is true, the second part is FALSE
TRUE or FALSE: a vector can be replaced by two other vectors that are at right angles to each other
TRUE
TRUE or FALSE: mass is a vector quantity
FALSE
TRUE or FALSE: wind velocity can be represented as a vector quantity
TRUE
TRUE or FALSE: whenever one object exerts a force on another object, the second object always exerts a force back on the first object
TRUE
TRUE or FALSE: a rocket ship is pushed forward by the gases that are forced out the back of the ship
TRUE
a boat is rowed at 4.0 km/h directly across a river in water that is flowing at right angles at 8.0 km/h. What is the resulting speed of the boat.
A^2 + B^2 = C^2
square root of 4^2 + 8^2
square root of 16 + 64
square root of 80
C = 8.944
8.94 km/h
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