Chapter 1: Patterns of Motion & Equilibrium
If you toss a ball straight upward at 40 m/s with no air resistance, one second before it reaches the top of its path its speed is
0
A sky diver with a mass of 100 kg experiences an air resistance of 600 N, and an acceleration of
0.4 g
A 1-N apple falls off your head. While the apple is freely falling, the magnitude of the net force on it is
1 N
Toss a ball upward at 10 m/s, and the time it takes to reach its highest point is about
1 second.
A 1- kg mass at Earth's surface weighs about
10 N
If a car increases its velocity from zero to 50 km/h in 5 seconds, its average acceleration is
10 km/h/s.
When you step off a bus moving at 10 m/s, your horizontal speed when you meet the ground is
10 m/s.
If you exert a horizontal 100-N force on a crate and it slides along a factory floor at constant speed, then the friction between the crate and the floor is
100 N.
Fido weighs 120 N and carries Trixie who weighs 40 N on her back. The support force on Fido's feet is Selected Answer:
160 N.
A boat travels upstream against a current of 3 m/sec. If the speedometer of the boat indicates it is traveling 5 m/sec relative to the water, its speed relative to a person standing on the shore would be Selected Answer:
2 m/sec
The tension in a rope that supports a 2-lb. bag of sugar hanging at rest is
2lb
If a Jaguar sports car accelerates from zero to 100 km/h in 3.0 s its acceleration is
33.3 km/h/s.
f a 100-lb. person steps on a pair of bathroom scales and leans so that the reading on one scale is 60 lbs., the reading on the other scale is
40 lbs.
An object is pulled northward with a force of 10 N and southward with a force of 15 N. The magnitude of the net force on the object is
5 N
Toss a ball upward at 30 m/s and if air drag is negligible, the ball will be in the air for
6 seconds.
If a 60-kg parachutist is falling downward at a constant speed (and the weight of the parachute itself can be neglected), the friction force on the parachutist must be Selected Answer:
600 N
Friction
A force that opposes motion between two surfaces that are in contact
Weight
A measure of the force of gravity on an object
Force
A push or a pull
Galileo discovered that something remains unchanged for balls rolling down inclined planes. What remains the same as motion progresses?
Change of speed is the same in equal times.
A free- falling object has a speed of 30 m/s at one instant. Exactly 2 seconds later its speed will be Selected Answer:
Correct 50 m/s.
kilogram
SI unit for mass
Newton
SI unit of force
Velocity
Speed in a given direction
Volume
The amount of space an object takes up
net force
The combination of all forces acting on an object
Speed
The distance an object travels per unit of time
support force
The force that supports an object against gravity
Acceleration
The rate at which velocity change (M/s^2)
vector quantity
a quantity that has both magnitude and direction
Tension forces are equal throughout the rope pull equally hard on both ends of the rope are parallel to the rope
all of the above properties
Vector
arrow that represents that magnitude and direction of quantity
The thing that distinguishes speed from velocity is
direction.
free fall
falling only under the influence of gravity- falling without air resistance
Compared with a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much
inertia, volume, Mass.
If you are carrying a heavy bag of groceries and bang your hand against the wall, the concept that best explains why you are hurt is
inertia.
If you have snow on your boots, you can get the snow off by stamping your boots on the floor. This is in accord with the law of
inertia.
A glance at your speedometer will tell you your Selected Answer:
instantaneous speed.
The hang time (time off the floor in an unassisted jump) of professional basketball players is typically
less than 1 second.
Galileo's demonstration at the Leaning Tower of Pisa
refuted Aristotle's teachings.
A roller coaster car at an amusement park carrying 1 passenger takes 3 min to make its ride from start to finish. Neglecting friction, a car with 5 passengers would take
same time.
Drop a ball and it accelerates at 10 m/s/s. If you instead throw it downward, then right after it leaves your hand, assuming no air drag, its acceleration is
still 10 m/s/s.
Swing a rock overhead in a horizontal circle, and if the string breaks the rock will follow a
straight-line path.
Mass
the amount of matter in an object
air resistance
the force of friction acting on an object due to its motion in air
A certain rock weighs 30 N on the moon. Meanwhile a particular brick weighs 30 N on the earth. Which one has the greater mass?
the rock on the moon
A force of 1 N accelerates a mass of 1 kg at the rate of 1 m/s per second. The acceleration of a mass of 2 kg acted upon by a force of 2 N is
the same
Inertia
the tendency of an object to resist any change in its motion
hang time
the time that one's feet are off the ground during a vertical jump
Equilibrium
the vector sum of forces acting on an object that is not accelerating
Speed is always measured in terms of a unit of distance and a unit of
time.
An object in motion tends to remain in motion
without the need of a force
Earth moves about 30 km/s relative to the Sun. When you jump upward in front of a wall, the wall doesn't slam into you at 30 km/s because the wall
you move at the same horizontal speed, before, during, and after your jump.
The net force on any object in equilibrium is
zero
The net force on any object moving at constant velocity is Selected Answer:
zero.
