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AP Physics 1 – Review of Major Concepts
**This document is intended to help you begin reviewing for both the AP Physics Midterm Exam and the AP
Physics 1 test. It is NOT all-inclusive, and so it should not be the only resource you use to study for either
exam.**
AP Physics 1 Midterm – 40 points total
Friday, January 8th (in class):
2 Free Response Questions
Monday, January 11th (during testing): 26 Multiple Choice Questions
14 points
26 points
Unit 1 – Kinematics
Summary: The entire goal of motion analysis is to describe, calculate, and predict where an object is, how fast
it’s moving, and how much its speed is changing.
Vocabulary: position, displacement, speed, velocity, acceleration, free fall, projectile
Equations: 𝑣𝑓 = 𝑣0 + 𝑎𝑡
1
∆𝑥 = 𝑣0 𝑡 + 2 𝑎𝑡 2
𝑣𝑓 2 = 𝑣0 2 + 2𝑎∆𝑥
(All on AP sheet)
Key Ideas
 In a position-vs-time graph, the object’s position is read from the vertical axis, and the object’s velocity
is the slope of the graph. The steeper the slope, the faster the object moves. Positive slope means the
object is moving in the positive direction, and negative slope means the object is moving in the negative
direction.
 In a velocity-vs-time graph, the object’s velocity is read from the vertical axis, and the object’s
acceleration is the slope of the graph. The object’s displacement is given by the area under the curve.
The location of the object can’t be determined, only how far it moved.
 Common Pitfall: Acceleration is different than velocity. The +/- for acceleration doesn’t say anything
about which way something is moving, unless you know whether it is speeding up or slowing down. (Ex:
negative acceleration can mean slowing down in the positive direction or speeding up in the negative
direction)
 The five motion variables are initial velocity, final velocity, displacement, acceleration, and time. If you
know any 3 of these variables, you can use the kinematic equations to solve for the others.
 When an object is in free fall, its acceleration is about 10 m/s2 towards the ground. “Free fall” means no
other forces other than gravity are acting on the object.
 A projectile has no horizontal acceleration and so moves at constant speed horizontally. A projectile is
in free fall, so its vertical acceleration is about -10 m/s2.
 To find the vertical component of a velocity at an angle, multiply the speed by the sine of the angle. To
find the horizontal component, use cosine. This works as long as the angle is measured from the
horizontal (as usual).
 Time is the bridge between horizontal and vertical parts of projectile motion.
 Common Pitfall: For horizontally launched projectiles, the height is the only thing that determines the
time the object takes to fall. (Remember the bullet fired vs. dropped Mythbusters?) Both height and
initial speed control the range of the projectile.
Unit 2 – Dynamics
Summary: A force is a push or pull applied by one object on another object.
Vocabulary: force, net force, weight, friction, static friction, kinetic friction, normal force, coefficient of friction,
Newton’s Laws (1st – inertia, 2nd – acceleration, 3rd – action/reaction), centripetal acceleration, centripetal force
Equations: 𝑎 =
𝐹𝑛𝑒𝑡
𝑚
𝐹𝑓 = 𝜇𝐹𝑁
𝑎𝑐 =
𝑣2
𝑟
(on AP Sheet)
You may also want to use weight = mg
Key Ideas:
 When drawing a free-body diagram, remember that only gravitational and electrical forces act without
contact. Surfaces exert 2 forces on objects – normal forces are perpendicular and friction forces are
parallel to the surface. Friction is a resistive force, so it always points opposite the motion.
 When an object moves along a surface, the acceleration in a direction perpendicular to that surface
must be zero. Therefore, the net force perpendicular to the surface is also 0. (Ex: for horizontal
motion, the upward and downward forces must balance out)
 Common Pitfall: Static friction is a maximum amount of force that must be overcome to get an object to
start moving. So, if you are drawing a free-body diagram of a situation where the force is not great
enough to overcome static friction, you should make the static friction force equal to the push or pull.
 Newton’s 3rd law states that the force of Object A on Object B is equal in amount and opposite in
direction to the force of Object B on Object A. The accelerations that the objects will experience due to
these forces are not necessarily equal.
 If the net force has both a vertical and horizontal component, use the Pythagorean Theorem to
determine the magnitude of the net force, and use inverse tangent to find the direction.
 When a force at an angle measured from the horizontal, the vertical component is the amount of force
times the sine of the angle, and the horizontal component is the amount of force time the cosine of the
angle.
 Newton’s 2nd law states that net force acting on an object is equal to the object’s mass times its
acceleration. Be sure to consider net force.
 On an inclined plane at an angle, break the weight into its components. The parallel component is equal
to the weight times the sine of the angle. The perpendicular component is weight times the cosine of
the angle.
 When an object moves in a circle, it has centripetal acceleration directed toward the center of the circle.
The force that keeps an object moving in a circle is also directed towards the center of the circle, and it
is called centripetal force.
Unit 3 – Gravitation
Summary: The force on an object due to gravity is mg, where m is mass and g is the gravitational field. The
gravitational field produced by an object depends on the mass of the object and the distance from the object’s
center.
Vocabulary: gravitational field, gravitational force, gravitation constant (G), free-fall acceleration (AKA
acceleration due to gravity), gravitational and inertial mass.
Equations: 𝐹𝑔 = 𝐺
𝑚1 𝑚2
𝑟2
(on AP Sheet)
You can solve for gravitational field g by dividing both sides by m, so
𝑀
that you have the equation 𝑔 = 𝐺 𝑟2 . We also set the gravitational force equal to centripetal force to find the
𝐺𝑀
.
𝑟
equation for orbital speed 𝑣 = √
Key Ideas
 The amount of gravitational field depends on 2 things: the mass of the planet creating the field (M) and
the distance you are from that planet’s center (r).
 The weight of an object – that is, the gravitational force of a planet on that object – is given by mg.
 Any two object exert gravitational forces (although sometimes miniscule ones) on each other. The
gravitational force between two objects is given by the equation for Fg above.
 Gravitational mass indicates how an object responds to a gravitational field. Inertial mass indicates how
an object accelerates in response to a new force. In every experiment ever conducted, an object’s
gravitational mass is equal to its inertial mass.
Unit 4 – Work, Energy, and Power
Summary: An object possesses kinetic energy by moving. Interactions with other objects can create potential
energy. Work is done when a force acts over a distance parallel to that force. When work is done on an object
(or system of objects), kinetic energy can change.
Vocabulary: kinetic energy, gravitational potential energy, mechanical energy, work, power
1
Equations: 𝐾 = 2 𝑚𝑣 2
∆𝐸 = 𝑊 = 𝐹𝑑 cos 𝜃
𝑃=
∆𝐸
𝑡
∆𝑈𝑔 = 𝑚𝑔∆𝑦
(on AP Sheet)
th
The 4 equation is for gravitational potential energy, but looks slightly different than how we learned it.
Key Ideas:
 Work is done when a force is exerted on an object and that object moves parallel to the direction of the
force. When force is directed in the same direction as the object’s motion, the work done is positive,
and when the force is exerted in the opposite direction (such as resistive forces) the work is negative.
 To lift an object to a greater height at a constant speed, the work done is calculated by
W=Fd = mgd
since the force would be equal to the weight. As you lift something, you are doing positive work on the
object, while gravity is doing negative work.
 A “conservative” force convert potential energy to other forms of mechanical energy when it does work.
Thus, a conservative force does not change the energy of a system. Gravity is an example of a
conservative force.
 A “nonconservative” force can change the mechanical energy of a system. Friction is an example of a
nonconservative force that decreases the mechanical energy of a system. The propeller of an airplane
could provide a nonconservative force that would increase the mechanical energy of the system.


The work-energy theorem can be stated in many different ways. One useful way to look at it might be
𝑊𝑛𝑐 = ∆𝐾𝐸 + ∆𝑃𝐸. If mechanical energy is conserved, then this means that as kinetic energy goes up,
potential energy must go down by the same amount (and vice versa) to balance out to 0. If there are
nonconservative forces, they must equal the balance of the change in mechanical energy.
Power = work/time. If two students are climbing the same set of stairs, their power will depend on their
masses (since they are lifting themselves to a higher height) and the time it takes them to climb the
stairs.
Unit 5 – Impulse and Momentum
Summary: Whenever you see a collision, the techniques of impulse and momentum are likely to be useful in
describing or predicting the result of the collision. In particular, momentum is conserved in all collisions – this
means that the total momentum of all objects is the same before and after the collision. When an object (or a
system of objects) experiences a net force, the impulse momentum theorem can be used for predictions and
calculations.
Vocabulary: momentum, impulse, system, elastic collision, inelastic collision, explosion, center of mass
Equations: 𝑝 = 𝑚𝑣
∆𝑝 = 𝐹∆𝑡 (on AP Sheet)
You may also want to combine these into 𝑚∆𝑣 = 𝐹∆𝑡.
We also used 2 equations for collisions (𝑚1 𝑣10 + 𝑚2 𝑣20 = 𝑚1 𝑣1𝑓 + 𝑚2 𝑣2𝑓
and 𝑚1 𝑣10 + 𝑚2 𝑣20 = 𝑚𝑡𝑜𝑡𝑎𝑙 𝑣𝑓 ) and one for explosions (𝑚𝑡𝑜𝑡𝑎𝑙 𝑣0 = 𝑚1 𝑣1𝑓 + 𝑚2 𝑣2𝑓 ) but these are all just
conservation of momentum in algebraic form.
Key Ideas:
 In any system in which the only force acting are between objects in that system, momentum is
conserved. This effectively means that momentum is conserved in all collisions.
 In elastic collisions, kinetic energy is conserved, as well as momentum.
 The center of mass of a system of objects obeys Newton’s second law. So if no external forces act on
colliding objects, the center of mass must stay at rest.