Chapter 2&3 physics
a car maintains a constant velocity of 100km/hr for 10 seconds. during this interval its acceleration is
zero
a car accelerates from rest for 5 seconds until it reaches a speed of 20m/s. what is the cars acceleration
4m/s
at one instant an object in free fall is moving downward at 50m/s. one second later its speed is approximately
60
at one instant an object in free fall is moving downward at 50 meters per second. one second later its speed should be about
60m/s
If a car increases its velocity from zero to 60km/h in 10 seconds, its acceleration is
6km/h/s
If a car accelerates from rest at 2 meters per second, its speed 3 seconds later would be about
6m/s
If a free falling object were somehow equipped with a speedometer, its speed reading would increase each second by about
10m's
an object at rest near the surface of a distant planet starts to fall freely. if the acceleration there is twice that of the earth, its speed one second later would be
20m/s
a package falls of a truck that is moving at 30m/s. neglecting air resistance. the horizontal speed of the package just before it hits the ground is
30
a car accelerates from rest from 5 seconds until it reaches a speed of 20m/s. what is the car's acceleration in meters per second
4
the first scientist to be credited for postulating that earth circled the sun was
Copernicus
the first scientist to be credited for postulating the earth circled the sun was
Copernicus
Aristotle and his followers for many centuries thought the earth was at rest at the center of the universe because
humans experience no sensation of a moving earth
when Galileo rolled a ball down one incline so that at the bottom it rolled up another, he found that the ball rolled
almost to its initial height
when the net force on something is zero we say it is
in mechanical equilibrium
a bullet is fired straight down from the top of a high cliff. neglecting air resistance, the acceleration of the bullet in meters per second
is 9.8
a vector quantity
is presented by an arrow, has direction, and has magnitude
Galileo taught us that if you roll a ball along a level surface it will
keep rolling if friction is absent
Galileo said that if you rolled a bag along a level surface it would
keep rolling without slowing if no friction acted upon it
a hockey puck sliding across the ice final come to rest because
of friction
according to Galileo, inertia is a
property of all matter
earliest n the most influential Greek philosopher was aristole who taught that
the four elements are earth,fire, water, and air. all motion is either natural or violent. violent motion requires a sustained push or pull
If an object moves with constant acceleration its velocity must
Change by the same amount each second
if no external forces are acting on a moving object, it will
Continue forever
the force of friction on a sliding object is 10n. the applied force needed to maintain constant velocity is
10
an object covers a distance of 8 meters in the first second of travel, another 8 meters during the next second, and 8 meters during the third second. its acceleration in meters per second is approximately
0
when a rock thrown straight up gets the exact top of its path its
0
two measurements necessary for calculating acceleration are
Distance and time
a hockey puck sliding across the ice finally comes to rest because of
Friction
the first scientist to introduce the concept of inertia was
Galileo
the scientist to first introduce the concept of inertia is
Galileo
the property of an object to resist change in motion is known as
Inertia
Every object continues in a state of rest of uniform speed in a straight line unless acted on by a nonzero net force is
Newton's first law of motion
a force is
both a push or pull
if an object moves with constant acceleration, its velocity must
change by the same amount each second
the two measurements necessary for calculating average speed are
distance and time
science greatly advanced when Galileo favored
experiment over philosophical discussions