Forces and Motion
The unit used to measure distance is
centimeters.
An athlete is running a 5-km race at an
average speed of 8 km/h. She has to
stop to tie her shoe. After tying her
shoe, she continues running at 8 km/h.
Why would her average speed for the
entire race be less than 8 km/h.
The total time she took to complete the
race decreased because she stopped.
An elevator traveled 15 floors (150 ft) at
a speed of 4.5 m/s. What additional
information is needed to determine the
velocity of the elevator.
The direction the elevator traveled.
The definition of motion is
A change in position over time.
Tyrone wants to determine how fast a bowling
ball travels when it is bowled. He uses a
stopwatch to record, in seconds, the time it
takes for the bowling ball to reach the pins.
What unit would be most appropriate to
measure the length of the bowling lane?
meters.
What two measurements are needed to
determine the speed of an object?
Distance and time
What is acceleration?
The rate at which velocity changes.
What is an example of acceleration?
A bus moves on a straight road and then
makes a right turn.
What is an example of
centripetal acceleration.
An object moving in a circle at 20m/s.
An example of a contact force is
Friction between an object and air.
An index card is placed across
the top of a drinking glass. A coin is then
placed on top of the index card. A student
quickly flicks the card sideways off the glass.
Which of Newton’s laws explains why the coin
falls into the glass rather than moving to the
side with the index card.
Newton’s first law of motion.
A moving object collides with a
stationary object. What is true
according to Newton’s third law of
motion?
Each object exerts a force on the other,
and the two forces are equal and in
opposite directions.
Objects with the greatest
mass and the closest will have
the greatest gravitational
force between them.
In order for a space shuttle to leave Earth, it
must produce a great amount of thrust. Its
rocket boosters create this thrusting force by
burning great amounts of fuel. However, once in
space, the shuttle needs very little fuel. It
circles Earth while gravity pulls it toward Earth.
What term describes the motion of the shuttle
around Earth?
orbit
High and low tides are the regular pattern of
rising and sinking ocean-water levels. They are
formed as a result of the gravitational forces
of the moon and sun on Earth’s oceans.
The moon has a greater effect on Earth’s
oceans than the sun. Why would the moon have a
greater effect than the sun?
The moon is closer to Earth than the sun.
What is gravity?
The force that pulls all objects toward
one another.
What is true of an object in free fall?
Only the force of gravity is accelerating
it.
Two objects have a certain gravitational
force between them. What would happen
if the mass of the objects suddenly
increased?
The gravitational force between the two
objects would increase.
Melanie watched the path a baseball
followed after a pitcher threw it. She
noticed that the ball traveled horizontally
away from the pitcher, as well as
downward toward the ground. What force
caused the ball to accelerate in the
downward direction when it was thrown?
Gravitational force
A skydiver jumps out of a plane.
She falls downward at a very fast speed.
When she opens her parachute, she slows
down. What force pulled the skydiver to
the ground?
gravity
What is air that moves from regions of
high pressure to regions of low pressure?
wind
How are water pressure and
atmospheric pressure similar?
They both result from the downward pull
of gravity
A student submerges a cube in a
container of water. How can the student
determine the buoyant force on the cube?
Measure the weight of the water
displaced by the cube
A weather forecaster is determining the
air pressure in order to describe the
weather conditions. What characteristic
of air is the weather forecasting
analyzing?
The force it exerts on a given area
A hiker is climbing a tall mountain. How
will atmospheric pressure at the top of
the mountain compare to the atmospheric
pressure at the bottom of the mountain?
The pressure decreases with elevation so
it will be lower at the top of the
mountain than at the bottom.
What equation describes the relationship
between pressure, force, and area?
Pressure = force/ area
What results from a difference in fluid
pressure?
A child drinks milk through a straw.
Rajiv made a model of a boat. When he
places it in water, it sinks. According to
Archimedes’ principle, why does the boat
sink?
The buoyant force is less than the boat’s
weight.