Exam 1 Flashcards
The first estimate of the size of the moon and the first written record for the sun centered cosmos are attributed to
aristarchus
When a rocket forces exhaust gases downward the exhaust gases
exert an upward force on the rocket
If an apple experiences a constant net force, it will have a constant
acceleration
the force of air resistance or air drag depends on
the speed that the object is raveling through the air and the frontal surface area
if you throw a rock upward at a speed of 50 m/s how long until the rock reaches its peak height?
5 s
Galileo taught us that if you roll a ball along a level surface it will
keep rolling if friction is absent
a large heavy truck and a small baby carriage roll down a hill. neglecting friction, at the bottom of the hill, the baby carriage will likely have
less momentum
when a pair of 10N forces acts on a box of candy, the net force on the box is
any of the above depending on the directions of forces
a force is a vector quantity because it has both
magnitude and direction
when the sun shines on the moon, the moon casts a shadow
- that is tapered
- at all times
- that sometimes falls on earth
the equilibrium rule applies to
- objects or systems in uniform motion in a straight line
- objects or systems at rest
you toss a ball and it makes a curved path. at the instant that the ball leaves your hand it has a velocity which has a horizontal component of 30 m/s and a vertical component of 20 m/s. how far from you does the ball land?
120 m
when you are moving at constant velocity, which of the following is NOT true
you are experiencing a non zero acceleration
a light woman and a heavy man jump from an airplane at the same time and open their same size parachutes at the same time. which person will get to state of zero acceleration first?
the light woman
student A has a mass of 95 kg and student B has a mass of 77 kg. they sit in identical office chairs facing each other. student A places his bare feet on the knees of student B as shown. student A suddenly pushes outward with his feet, causing both chairs to move. during the push while the students are still in contact with one another
each student exerts the same amount of force on the other
Copernicus and Aristarchus shared the view that was against Aristotelian dogman, namely that
the sun was the center of the cosmos and the earth moves; it orbits the sun
the greek mathematician Eratosthenes made observations of sunlight striking water in the bottom of a well and also shadows cast in a neighboring town to find the size of
earth
a freely falling watermelon falls with constant
acceleration
a vehicle undergoes acceleration when it
- gains speed
- loses speed
- changes its direction
which of the following is not a vector?
speed
a moving van with a stone lightly glued to the midpoint of its ceiling smoothly moves at constant velocity. when the glue gives way, the stone falls and hits the floor
exactly below the midpoint of the ceiling
two metal balls are the same size but one weighs twice as much as the other. the balls are dropped from the roof of a single story building at the same instant of time. the time it takes the balls to reach the ground below will be
about the same for both balls
a stone dropped for the roof of a single story building to the surface of the earth
speeds up because of an almost constant force of gravity acting upon it
a 10 N falling object encounters 10 N of air resistance, the net force on the object is
0 N
a truck traveling 60 mph can be brought to a stop by hitting a large hay stack or it can be brought to a stop by hitting a brick wall. physics says
the impulse is the same either way but hitting the hay stack reduces force involved by extending the time of the impact
which of the following is NOT a characteristic of a scientific hypothesis?
once proved correct by one experiment, it can never be proved wrong by any experiment
the force with which earth pulls on the moon is
equal in magnitude to the force that moon pulls on earth
if a stone falls to the bottom of a mine shaft in 6 seconds, then the depth of the shaft is about
180 m
a skydiver steps from a helicopter and falls for a few seconds until terminal velocity is reached. thereafter, until he opens his parachute, his acceleration
is zero
a 600 N man stands at rest on two bathroom scales so that his weight is distributed evenly over both scales. the reading on each scale is
300 N
a woman exerts a constant horizontal force on a large box. as a results, the box moves across a horizontal floor at a constant sped. the constant horizontal force applied by the woman
has the same magnitude as the total force which resists the motion of the box
if a car increases its velocity from zero to 60 m/s in 10 seconds, its acceleration is
6 m/s2
when no force act on moving objects their paths are normally
straight lines
you throw a rock upward. the speed of the rock is 30 m/s when it leaves your hand. which of the following is false?
at the peak of the trajectory, the acceleration due to the force of gravity on the rock is zero
a humming bird flying at 4 km/h that gets caught in a 3 km/h crosswind has a resultant speed of about
5 km/h
in physics we seek
to describe nature and understand its rules
the weight of a full liter jug of water on the surface of the moon is
less than it is here on the surface of earth
Aristotle believed all of the following except
in the absence of air resistance heavy and light objects dropped from the same height reach the ground at the same time
if a freely falling object were equipped with a speedometer, its speed reading would increase each second by about
5 m/s
