physics main review
*orbital motion acceleration equation
a = (vorbit)^2/r = g
*orbital motion acceleration equal to all this
a = Fnet/m = w/m = g
*mass
a quantity that describes an object's inertia, its tendency to resist being accelerated
An object is moving with constant non-zero acceleration in the +x direction. The velocity versus time graph of this object is
a straight line making an angle with the time axis.
*the forces acting on an object determine its
acceleration
*static equilibrium
an object at rest
Which of the following situations is impossible? A) An object has velocity directed east and acceleration directed west. B) An object has velocity directed east and acceleration directed east. C) An object has zero velocity but non-zero acceleration. D) An object has constant non-zero acceleration and changing velocity. E) An object has constant non-zero velocity and changing acceleration.
an object has constant non-zero velocity and changing acceleration.
*newton's first law
an object has no forces acting on it. if it is at rest, it will remain at rest. if it is moving, it will continue to move in a straight line at a constant speed
*regular acceleration equation
ax = dvx/dt = ((vx)f-(vx)i)/dt
A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will
be directly over the package
*action and reaction forces act on
different objects
*Tension _ when a rope passes over a massless, frictionless pulley
does not change
*free fall acceleration always point _ no matter which direction object is moving
down
*A string or rope pulls what it's connected to with a force _ its tension
equal to
*The tension in a rope is _ the force pulling on the rope
equal to
A bucket is being lowered by a very light rope with a constant downward velocity. The tension in the rope must be
equal to the weight of the bucket
An object of weight W is in freefall close to the surface of Earth. The magnitude of the force that the object exerts on Earth is
equal to w
*frequency equation for uniform circular motion
f = 1/T
A block of mass m sits at rest on a rough inclined ramp that makes an angle θ with the horizontal. What must be true about force of static friction f on the block?
f = mg cos θ
1) In a collision between a huge SUV and a small hybrid car, the SUV exerts a larger force on the hybrid than the hybrid exerts on the SUV. A) True B) False C) It depends on whether the collision is a head-on collision or a rear-end collision.
false
If the acceleration of an object is zero, then that object cannot be moving.
false
If the velocity of an object is zero at some point, then its acceleration must also be zero at that point.
false
If the velocity of an object is zero, then that object cannot be accelerating.
false
In order to lift a bucket of concrete, you must pull up harder on the bucket than the bucket pulls down on you.
false
a vector pointing upward has a positive magnitude, a vector pointing downward has a negative magnitude.
false
*kinetic friction force equation
fk = uk*n
When a car turns a corner on a level road, which force provides the necessary centripetal acceleration
friction
*maximum static friction equation
fsmax = us*n
*any object moving under the influence of _, and no other force, is in free fall
gravity only
An elevator suspended by a vertical cable is moving downward but slowing down. The tension in the cable must be
greater than the weight of the elevator
A 10-kg rock and a 20-kg rock are thrown upward with the same initial speed v0 and experience no significant air resistance. If the 10-kg rock reaches a maximum height h, what maximum height will the 20-kg ball reach?
h
to figure it out which car has traveled the farthest, it is the graph that
has the most area under the line of the graph
*range of projectile
horizontal distance traveled
*As an object falls farther, it's speed and drag forcer
increase
*gravity obeys _ law
inverse square
If a satellite moves with constant speed in a perfectly circular orbit around the earth, what is the direction of the acceleration of the satellite?
inward toward the earth
When a ball is thrown straight up with no air resistance, the acceleration at its highest point
is downward
An object moving in the +x direction experiences an acceleration of +2.0 m/s2. This means the object
is increasing its velocity by 2.0 m/s every second.
A person who normally weighs 700 N is riding in an elevator that is moving upward but slowing down at a steady rate. If this person is standing on a bathroom scale inside the elevator, what would the scale read?
less than 700 N
Two boxes P and Q on a perfectly smooth horizontal surface are connected by a light horizontal cord. The mass of P is greater than that of Q. A horizontal force F is applied to box Q as shown in the figure, accelerating the bodies to the right. The magnitude of the force exerted by the connecting cord on body P is
less than f but not 0
*Just after an object is released from rest, its speed is _ and its drag force is _
low, small
The acceleration due to gravity is lower on the Moon than on Earth. Which one of the following statements is true about the mass and weight of an astronaut on the Moon's surface, compared to Earth?
mass is the same, weight is less
If the velocity versus time graph of an object is a straight line making an angle of +30° (counter clockwise) with the time axis, the object is
moving with constant non-zero acceleration.
*in both types of equilibrium there is no
net force acting on the object
A crate is sliding down an inclined ramp at a constant speed of 0.55 m/s. The vector sum of all the forces acting on this crate must point A) down the ramp. B) up the ramp. C) perpendicular to the ramp. D) vertically downward. E) None of the above choices is correct.
none of the above, since they're equal
*In uniform circular motion, it's velocity is _ because
not constant, because the direction of motion is always changing
*frequency
number of revolutions per second
As shown in the figure, a woman is straining to lift a large crate, but without success because it is too heavy. We denote the forces on the crate as follows: P is the magnitude of the upward force being exerted on the crate by the person, C is the magnitude of the vertical contact force on the crate by the floor, and W is the weight of the crate. How are the magnitudes of these forces related while the person is trying unsuccessfully to lift the crate?
p + c = w
*forces always occur in
pairs
*mass is a _ quantity, weight is a _ quantity
scalar, vector
Suppose that an object is moving with a constant velocity. Which statement concerning its acceleration must be correct? A) The acceleration is constantly increasing. B) The acceleration is constantly decreasing. C) The acceleration is a constant non-zero value. D) The acceleration is equal to zero.
the acceleration is equal to zero
A ball is thrown horizontally from the top of a tower at the same instant that a stone is dropped vertically. Which object is traveling faster when it hits the level ground below if neither of them experiences any air resistance?
the ball
*For circular motion at a constant speed, the acceleration vector a points toward
the center of the circle
An object is moving with constant non-zero velocity. Which of the following statements about it must be true? A) A constant force is being applied to it in the direction of motion. B) A constant force is being applied to it in the direction opposite of motion. C) A constant force is being applied to it perpendicular to the direction of motion. D) The net force on the object is zero. E) Its acceleration is in the same direction as it velocity.
the net force on the object is zero
You push on box G that is next to box H, causing both boxes to slide along the floor, as shown in the figure. The reaction force to your push is A) the push of box G on box H. B) the push of box H on box G. C) the push of box G against you. D) the upward force of the floor n box G. E) the acceleration of box G.
the push of box g against you
*An object on a rope is continuously lowered at constant speed. Which of the following is true?
the rope's tension = the object's weight
*The tension in a massless rope is _ at _ points in the rope
the same, all
If you pound a feather with a hammer, which one feels a greater force?
the size of the force is the same on both of them
From the edge of a roof top you toss a green ball upwards with initial speed v0 and a blue ball downwards with the same initial speed. Air resistance is negligible. When they reach the ground below
the two balls will have the same speed.
You are standing in a moving bus, facing forward, when you suddenly slide forward as the bus comes to an immediate stop. What force caused you to slide forward? A) gravity B) the normal force due to your contact with the floor of the bus C) the force due to friction between you and the floor of the bus D) There is not a force causing you to slide forward - it is due to inertia.
there is no force causing you to slide forward, it is due to inertia
A jet plane is speeding down the runway during takeoff. Air-resistance is not negligible. Identify the forces on the jet.
thrust, drag, w, n
Consider a deer that runs from point A to point B. The distance the deer runs can be greater than the magnitude of its displacement, but the magnitude of the displacement can never be greater than the distance it runs.
true
*The tension in a massless string is _ by passing over a massless, frictionless pulley
unchanged
*velocity equation for uniform circular motion
v = (2*pie*r)/T = 2*pie*f*r
*regular velocity equation
v = displacement/time interval = dx/dt
*force is a _ quantity
vector
The slope of a position versus time graph gives
velocity
*speed of object in orbit equation
vorbit = square root of (g*r)
*critical speed equation for uniform circular motion
w = (m*(vc^2))/r
*weight equation
w=mg
When is the average velocity of an object equal to the instantaneous velocity?
when the velocity is constant
*To find the direction of fs, decide
which way the object would move if there were no friction.
*2nd kinematic equation for position with constant acceleration
xf = xi + (vx)i*dt +1/2*ax*(dt)^2
*range of projectile equation
((v^2)/g) sin (2θ)
*1st kinematic equation for velocity with constant acceleration
(vx)f = (vx0i +ax*dt
*3rd kinematic equation for velocity/displacement with constant acceleration
(vx)f^2 = (vs)i^2 +2*ax*dx
*net force producing centripetal acceleration of uniform circular motion
-->Fnet = m*-->a = (m*v^2)/r
*centripetal acceleration of object in uniform circular motion equation
-->a = (v^2)/r
*newton's second law equation
-->a = -->Fnet/m
Which of the following quantities has units of a displacement? (There could be more than one correct choice.) A) 32 ft/s2 vertically downward B) 40 km southwest C) 9.8 m/s2 D) -120 m/s E) 186,000 mi
40 km sw, 186000 miles
A car is able to stop in a distance d. Assuming the same braking force (and therefore the same acceleration), what distance does this car require to stop when it is traveling twice as fast?
4d
Car A is traveling at twice the speed of car B. They both hit the brakes at the same time and decrease their velocities at the same rate. If car B travels a distance D before stopping, how far does car A travel before stopping?
4d
A person who normally weighs 700 N is riding in a rather swift elevator that is moving at a constant speed of 9.8 m/s. If this person is standing on a bathroom scale inside the elevator, what would the scale read?
700 N
*centripetal acceleration
An acceleration that always points directly toward the center of a circle
*dynamic equilibrium
An object moving in a straight line at a constant speed
A 20-ton truck collides with a 1500-lb car. Which of the following statements must be true?
During the collision, the force on the truck is equal to the force on the car.
*newton's second law equation in component form
EFx = m*ax and EFy = m*ay
*newton's second law in component form
EFx = m*ax and EFy = m*ay
*comparing forces and masses equation
F 1 on 2 = F 2 on 1 = (G*(m1*m2))/r^2
A block of mass m sits at rest on a rough inclined ramp that makes an angle θ with the horizontal. What must be true about normal force F on the block due to the ramp?
F = mg cos θ
*law of inertia
In the absence of friction, if the sled is moving, it will stay in uniform motion in a straight line
In the figure, a 10-lb weight is suspended from two spring scales, each of which has negligible weight. Which one of the following statements about the readings in the scales is true? A) Each scale will read 5 lb. B) The top scale will read zero, the lower scale will read 10 lb. C) The lower scale will read zero, the top scale will read 10 lb. D) Each scale will show a reading between one and 10 lb, such that the sum of the two is 10 lb. However, exact readings cannot be determined without more information. E) None of these is true.
None because each scale will read 10 lb
*period of object in orbit equation
T = (2*pie*r)/vorbit = 2*pi*square root of (r/g)
A ball at the end of a string is being swung in a horizontal circle. What force is producing the centripetal acceleration of the ball?
Tension in the string
*accuracy
The extent to which a given measurement agrees with the standard value for that measurement.
*precision
The extent to which a given set of measurements of the same sample agree with their mean.
*terminal speed
The speed at which the exact balance between the upward drag force and the downward weight force causes an object to fall without acceleration
*period
The time interval it takes an object to go around a circle one time
*weight
Weight is the gravitational force exerted on an object by a planet
*newton's third law of motion
Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first
