Section 1
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A 300-kg bear grasping a vertical tree slides down at constant velocity. The friction force between the tree and the bear is
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Date created
Mar 14, 2020
Cards (73)
Section 1
(50 cards)
A 300-kg bear grasping a vertical tree slides down at constant velocity. The friction force between the tree and the bear is
3000N
The conservation of momentum is most closely related to
Newton's 3rd law
Suppose you roll a ball off a tabletop. Will the time to hit the floor depend on the speed of the ball?
Yes. (because the horizontal component of velocity combined with the vertical component results in a greater speed. That is why the ball travels a longer distance in the same amount of time)
Suppose you roll a ball off a tabletop. Will the time to hit the floor depend on the speed of the ball?
No (because the vertical velocity is independent of the horizontal)
The famous Leaning Tower of Pisa doesn't topple over because its center of gravity is
above a place of support
An object in mechanical equilibrium is an object
at rest moving with constant velocity having no acceleration
When an Earth satellite is placed into a higher orbit, what happens to its period?
increases
When a twirling ice skater brings her arms inward, her rotational speed
increases
In an accidental explosion, a satellite breaks in half while in circular orbit about Earth. One half is brought momentarily to rest. What is the fate of half brought to rest? What happens to the other half?
the half brought to rest falls to Earth and the other half's velocity doubles
Hang from a pair of gym rings and the upward support forces of the rings will always
add up to equal your weight
Whereas Aristotle relied on logic in explaining nature, Galileo relied on
experiment
Two billiard balls having the same mass and speed roll toward each other. What is their combined momentum after they meet?
0
The two measurements necessary for calculating average speed are
distance and time
A torque acting on an object tends to produce
rotation
The synthesis of a large collection of information that contains well-tested and verified hypotheses about certain aspects of the world is known as a scientific
theory
A karate expert executes a swift blow and breaks a cement block with her bare hand. The magnitude of the force experienced by her hand is
identical to the force applied
A 1-kg mass at the Earth's surface weighs how many N?
9.8 N
A 4 kg ball has a momentum of 12 kg m/s. What is the ball's speed?
3m/s p = mv p/m= v v =12/4 = 3m/s
In science, facts
may change
Mars has about 1/9 the mass of Earth. If Mars were somehow positioned into the same orbit as Earth's, how would its time to circle the Sun compare with Earth's?
it would be the same
The force on an apple hitting the ground depends upon
the speed of the apple just before it hits. the time of impact with the ground. whether or not the apple bounces.
A truck is moving at constant velocity. Inside the storage compartment, a rock is dropped from the midpoint of the ceiling and strikes the floor below. The rock hits the floor
exactly below the midpoint of the ceiling
The force of friction on a sliding object is 10 N. The applied force needed to maintain a constant velocity is
10N
Two objects have the same size and shape, but one is much heavier than the other. When they are dropped simultaneously from a tower, they reach the ground at the same time, but the heavier one has a greater
momentum
It is correct to say that impulse is equal to
the change in momentum
A broom is easier to balance on its end when the heavier end (the brush end) is
highest, farthest from your hand
If you toss a ball vertically upward in a uniformly moving train, it returns to its starting place. Will it do the same if the train is accelerating?
No (since the train is accelerating and the ball is moving at a constant velocity.)
A car maintains a constant velocity of 100 km/hr for 10 seconds. During this interval its acceleration is
zero
Science is a body of knowledge that
describes order in nature is an ongoing activity of humans condenses knowledge into testable laws
A horse gallops a distance of 10 kilometers in a time of 30 minutes. Its average speed is
20 km/h
The power required to exert 1 N force, over a distance of 1 m in 1 second is
1W
For a system in mechanical equilibrium the resultant forces and torques
must both be zero.
To catch a ball, a baseball player extends the hand forward before impact with the ball and then lets it ride backward in the direction of the ball's motion. Doing this reduces the force of impact on the player's hand principally because the
time of impact is increased
On a balanced seesaw, a boy three times as heavy as his partner sits
1/3 the distance from the fulcrum
Put a pipe over the end of a wrench when trying to turn a stubborn nut on a bolt, to effectively make the wrench handle twice as long, you'll multiply the torque by
2
In science, an educated guess is a
hypotheses
When bullets are fired from an airplane in the forward direction, the momentum of the airplane will be
decreased
An industrial flywheel has a greater rotational inertia when most of its mass is
nearest the rim
A park ranger shoots a monkey hanging from a branch of a tree with a tranquilizing dart. The ranger aims directly at the monkey. The monkey lets go of the branch as soon as the ranger shoots. Will the monkey be hit?
yes
A circularly moving object requires a centripetal force. What supplies this force for satellites that orbit Earth?
gravity
The impulse-momentum relationship is a direct result of
Newton's 2nd law
A 1-kg rock is suspended from the tip of a meter stick at the 0-cm mark so that the meter stick balances like a seesaw when the fulcrum is at the 25-cm mark. From this information, what is the mass of the meter stick?
1kg
Suppose that a tiny gun made of a strong but very light material fires a bullet that is more massive than the gun itself. For such a weapon
the target would be safer than the shooter
Padded dashboards in cars are safer in an accident than non-padded ones because an occupant hitting the dash has
increased time of impact
A rifle recoils while firing a bullet. The speed of the rifle's recoil is small because the
rifle has much more mass than the bullet
The scientist to first introduce inertia:
Galileo
Toss a baseball bat into the air and it wobbles about its
center of mass
Which planets have a more than one Earth year period, planets nearer or farther from the sun?
planets farther form the sun
Suppose the circumference of a bicycle wheel is 2 meters. If it rotates at 1 revolution per second when you are riding the bicycle, then your speed will be
2 m/s
A vehicle that weights 400 N on the surface of the Earth is traveling in outer space at a speed of 400 m/s. It can be stopped by applying a constant force of 20 N for
800 seconds
Section 2
(23 cards)