solutions
Define displacement, velocity, speed, and acceleration. In what units are they measured? -
**🔰 VERIFIED ANSWERS🔰 ✔✔Displacement: (∆s or d) = change in position
(magnitude=net distance or the distance from start to finish) [m]
(instantaneous) velocity: v=rate of change of position=∆s/∆t [m/s]
speed= magnitude of velocity [m/s]
acceleration: a=rate of change of velocity=∆v/∆t [m/s²]
State each of the Big Kinematics equations. Under what conditions can they be applied? -
**🔰 VERIFIED ANSWERS🔰 ✔✔d=½(v₀ + v)t
v=v₀ + at
d=v₀t ± ½at²
v²=v₀² + 2ad
These equations can only be applied when the acceleration is constant (uniform)
Give the magnitude and direction of free-fall acceleration near the surface of the Earth. -
**🔰 VERIFIED ANSWERS🔰 ✔✔g=9.8 m/s² = 10 m/s²
Direction of g is downward (toward surface of the Earth, radially toward center)
Define 'inertia". How is it measured? State Newton's Law of Inertia. - **🔰 VERIFIED
ANSWERS🔰 ✔✔Inertia is an object's natural resistance to change in its state of motion.
It is measured by mass, in kg
Fnet = 0 → v = constant
State Newton's Second Law of Motion. Define 'net force'. In what units is it expressed? -
**🔰 VERIFIED ANSWERS🔰 ✔✔Fnet = ma, where net force=sum of all forces that act on
the object (mass m).
,Force is measured in newtons (N); 1 N = 1 kg×m/s²
State Newton's Third Law of Motion. - **🔰 VERIFIED ANSWERS🔰 ✔✔If Object 1 exerts
a force on Object 2 ("action"), the Object 2 exerts an equal but opposite force back on Object
1 ("reaction")
Define 'weight'. Give at least two reasons why mass is different from weight. - **🔰
VERIFIED ANSWERS🔰 ✔✔Weight is the gravitational force acting on an object. It varies
with location and is measured in newtons.
Mass is not a force and does not vary in location (ex; on Earth versus on the moon).
It is measured in kilograms
State Newton's Law of Gravitation. - **🔰 VERIFIED ANSWERS🔰 ✔✔Every pair of
objects exert a gravitation attraction on each other, with strength F=GMm/r², where G is
the universal gravitational constant, m₁ and m₂ are the masses, and r is the (center of mass
to center of mass) distance between the objects
Define 'normal force'. Is the magnitude of the normal force on an object always equal to the
object's weight? - **🔰 VERIFIED ANSWERS🔰 ✔✔Fn (or N) is the component of the
contact force exerted by a surface that is perpendicular to the surface
Not always equal to the object's weight
Define 'friction'. Give the equation for the force of kinetic friction. Is there an equation for
the force of static friction? - **🔰 VERIFIED ANSWERS🔰 ✔✔f is the component of the
contact force exerted by a surface that is parallel to the surface.
fk = µkFn
No, there is only a formula for the maximum force of static friction Fs,max = µsFn
Define 'center of mass'. How is this point located? - **🔰 VERIFIED ANSWERS🔰 ✔✔CM
= point where all the object's mass can be considered to be concentrated = point that
behaves as if the object were a single particle = the balance point
, For objects of masses m₁, m₂, ... at coordinates x₁, x₂, ... the xcm = m₁x₁ +m₂x₂ +...)/(m₁ +
m₂)
Define 'uniform circular motion', 'centripetal acceleration', and 'centripetal force'. Give the
formulas for the magnitudes of centripetal acceleration and centripetal force. What are their
directions? - **🔰 VERIFIED ANSWERS🔰 ✔✔UCM= constant-speed motion in a circle
ac=acceleration toward center of circle necessary to keep object on circular path without
changing its speed
Fc= net force necessary to cause centripetal acceleration
ac= v²/r and Fc=ma=mv₂/r (where v=speed of object, r=radius of circle, m=mass of
moving object
Define 'torque' and 'lever arm'. Give two equations for calculating torque. - **🔰 VERIFIED
ANSWERS🔰 ✔✔Intuitively, torque is a quantity associated with a force F that measures
F's effectiveness at producing rotational acceleration. Lever arm, L, is the distance from the
pivot point to the line of action of the force, so that the lever arm is perpendicular to F.
Torque: rFsinθ = LF
Define 'equilibrium'. - **🔰 VERIFIED ANSWERS🔰 ✔✔An object is in equilibrium if
Fnet=0 and net torque=0
Define 'momentum'. Is it a vector or is it a scalar?
Define 'impulse'. Is it a vector or it is a scalar? - **🔰 VERIFIED ANSWERS🔰 ✔✔Linear
momentum= mass × velocity; p = mv
Impulse = force × time; J = F∆t
Both p and J are vectors
State the Law of Conservation of Momentum - **🔰 VERIFIED ANSWERS🔰 ✔✔If no net
external force acts, then total momentum is conserved in a collision or brief event