**** YOU PHYSICS
Two identical gliders slide toward each other on an air track. One moves at 2 m/s and the other at 1 m/s. If they stick together, the combination slides at
0.5 m/s= have to account for the doubled mass
An object is dropped and freely falls to the ground with an acceleration of 1 g. If it is thrown upward at an angle instead, its acceleration will be
1 g downward
A rifle of mass 2 kg is suspended by strings. The rifle fires a bullet of mass 0.01 kg at a speed of 200 m/s. The recoil velocity of the rifle is about
1 m/s
When a 10-kg block is simultaneously pulled westward with 25 N and eastward with 15 N, it undergoes an acceleration of
1 m/s/s to the West.
Toss a ball upward at 10 m/s, and the time it takes to reach its highest point is about
1 second
A piece of putty moving with 1 unit of momentum strikes and sticks to a heavy bowling ball that is initially at rest. After the putty sticks to the ball, both move with a combined momentum of
1 unit.
When a 25-N falling object encounters 15 N of air resistance, the net force on it is
10 N and it accelerates downward at less than g.
If a car increases its velocity from zero to 50 km/h in 5 seconds, its average acceleration is
10 km/h/s.
A buoyant force is the greatest on a submerged
10-newton larger-sized block of aluminum. ( aluminum is lighter so larger? )
According to the work-energy theorem, in the absence of friction, if you do 100 J of work on a cart, you'll increase its kinetic energy by
100 J
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
A gun with a muzzle velocity of 100 m/s is fired horizontally from a tower. Neglecting air resistance, how far downrange will the bullet be 1 second later?
100 meters
If Superman in space throws a boulder with 10 times as much mass as himself, and the boulder leaves his hands at 100 km/h, how fast does superman recoil?
1000 km/h
A man leans over the edge of a cliff and throws a rock upward at 5 m/s. Neglecting air resistance, two seconds later the rock's speed is
15 m/s.
Which requires more power, lifting a 25-kg bag of cement 10 m vertically in 1 minute, or lifting a 50-kg. bag 5 m vertically in 2 minutes?
25-kg bag.
A 4 kg ball has a momentum of 12 kg m/s. What is the ball's speed?
3 m/s
A 2000 kg car experiences a braking force of 10,000 N and skids to a stop in 6 seconds. The speed of the car just before the brakes were applied was
30 m/s.
A truck moves with a certain momentum. If both its speed and its mass are doubled, how much greater is its momentum?
4 times
Two identical arrows, one with twice the speed of the other, are fired into a hay bale. The faster arrow will penetrate
4 times as far
A bow is drawn so that it has 40 J of potential energy. When fired, the arrow will ideally have a kinetic energy that is
40 J
f a 100-pound person steps on a pair of bathroom scales and leans so that the reading on one scale is 60 pounds, the reading on the other scale is
40 pounds.
A 1 kg ball dropped from a height of 2 m rebounds only 1.5 m after hitting the ground. The amount of energy converted to heat is about
5 J
A 10 kg block with an initial velocity of 10 m/s slides 10 meters across a horizontal surface and comes to rest. It takes the block 2 seconds to stop. The stopping force acting on the block is about
50 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.
At one instant an object in free fall is moving downward at 50 m/s. One second later its speed should be about
60 m/s
A horse gallops a distance of 10 km in a time of 30 min. Its average speed is
A horse gallops a distance of 10 km in a time of 30 min. Its average speed is
Which is the smallest particle of those listed below?
A quark
A satellite near the Earth's surface makes a full circle in about an hour and a half. How long would a satellite located as far away as the Moon take to orbit the Earth?
About 28 days.
A massive fast-moving car collides head on with a light slow-moving car. The force of impact is greater on the
Actually, the force is the same on each
Atoms are generally smaller than
All of these (expect for a quark and nurons and what not)
Why is your weight not one-quarter as much when you climb to the top of a twice as tall tree?
Because you're not twice as far from Earth's center.
How far must one travel to get away from the Earth's gravitational field?
Forget it; you can't travel far enough.
Consider molecules of hydrogen gas and heavier molecules of oxygen gas that have the same kinetic energy. The molecules with more speed are
Hydrogen
A fast-moving massive car has a head-on collision with a slow-moving light car. Upon which is the impulse greater?
Impulse is the same on both.
Can all of the matter in the universe be listed in the Periodic Table of the elements?
No
what prevents satellites such as a space shuttle from falling?
Nothing; they're falling continuously all around the Earth.
Which have existed for a longer time, atoms that comprise the body of an old person, or those in the body of a newborn?
Same for each
Which of the following is a scientific hypothesis?
The Moon is made of green cheese.
If your speeding car slams into a haystack and comes to rest, how will the IMPULSE that acts on it compare with slamming into a brick wall and coming to rest?
The amount of impulse will be the same either way.
Push a cart along a track so twice as much net force acts on it. If the acceleration remains the same, what is a reasonable explanation?
The mass of the cart doubled when the force doubled.
In science, a theory is
a synthesis of a large body of well-tested knowledge.
Gravity accounts for?
all of these
The amount of gravitational force that acts on the space shuttle while in orbit is
almost as much as the shuttle's weight on the Earth's surface.
For the astronauts inside the orbiting space shuttle, there is no force of Earth gravity acting on them. This statement is
always false.
Inside a free-falling runaway elevator, your
apparent weight is zero
A heavy object and a light object are dropped at the same time from rest in a vacuum. The heavier object reaches the ground
at the same time as the lighter object.
Which has more momentum, a speeding baseball or an ocean liner at rest in a harbor?
baseball
As a helium-filled balloon rises in the air, it becomes
bigger
Which requires more work, lifting a 25-kg bag of cement 10 m vertically, or lifting a 50-kg bag 5 m vertically?
both the same
Water pressure is greatest against the
bottom of a submerged object
If an object moves with constant acceleration, it velocity must
change by the same amount each second.
The thing that distinguishes speed from velocity is
direction
When a bat hits a ball, the ball simultaneously
exerts the same amount of force on the bat.
A boat loaded with scrap iron floats in a swimming pool. When the iron is thrown overboard, the pool level will
fall
Toss a rock straight up in the air, and at the top of its path its acceleration is
g =10 m/s
The scientific method is a method for
gaining new knowledge.
Consider drops of water that leak at a steady rate from a dripping faucet. As the drops fall they
get farther apart.
If an object falling freely were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be
greater than the second before.
A cannon with a long barrel fires a shell faster because the shell experiences a greater
impulse
If the mass of the Earth somehow increased with no change in radius, your weight would
increase also (proportionally)
If a fast-moving object strikes you, you'll experience less force of impact if you can
increase the time the momentum decreases.
If you squeeze a bag of air to 80 percent of its volume, pressure inside will
increase to 125 percent
As a falling object gains speed in falling, air drag on it
increases
If an object's mass is decreasing while a constant force is applied to the object, the acceleration
increases.
The volume of water displaced by a floating 20-ton boat
is the volume of 20 tons of water.
Consider a cart pushed along a track with a certain force. If the force remains the same while the mass of the cart decreases to half, the acceleration of the cart
it will double
A pair of tennis balls fall through the air from a tall building. One of them is filled with lead pellets [do not neglect air resistance]. The ball to reach the ground first is the
lead filled ball
A lobster crawls onto a bathroom scale submerged at the bottom of the ocean. Compared to its weight above the surface, the lobster will have an apparent weight under water that is
less
A lunar month is about 28 days, If the moon were farther from the Earth that it is now, the lunar month would be
more than 28 days
If a monkey floating in outer space throws his hat away, the hat and the monkey will both
move away from each other, but at different speeds
A falling object that has reached its terminal velocity continues to
neither
A horse exerts 500 N of force on a heavy wagon. The wagon pulls back on the horse with an equal force. The wagon still accelerates because
nevertheless there is still an unbalanced force on the wagon
Joe can jump vertically 1 meter from his skateboard when it is at rest. When the skateboard is moving horizontally, Joe can jump
no higher
While a car travels around a circular track at a constant speed its
none of these.
Speed is always measured in terms of a unit of distance and a unit
of time
If the radius of Earth somehow bloated to twice its size, with no changes in mass, your weight at Earth's new surface would be
one quarter
A one-ton blimp hovers in the air. The buoyant force acting on it is
one ton
The force exerted on the tires of a car to directly accelerate it along the road is exerted by the
pavement
When water is turned on in a shower, the shower curtain moves towards the water. This has to do with
pressure of a moving fluid
The weight of an atom has most to do with its
protons.
Joe pushes Bill, who is asleep. Bill
pushes Joe equally hard even without waking up.
The team to win in a tug-of-war is the team that
pushes harder on the ground.
When a star collapses to form a black hole, its mass
remains the same
A rock is thrown upward at 50 degrees with respect to horizontal. As it rises, its horizontal component of velocity
remains unchanged
Compared to the buoyant force that acts on an object when it floats in fresh water, the buoyant force that acts on the same object when it floats in the dense water of the Dead Sea is
same
A black hole is
simply the remains of a giant star that has undergone gravitational collapse.
A massive fast-moving car collides head on with a light slow-moving car. The acceleration is greater on the
small car
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
still 10m/s/s
if we doubled the magnifying power of the most powerful optical telescope in the world, we would
still not be able to see or photograph an atom.
Swing a rock overhead in a horizontal circle, and if the string breaks the rock will follow a
straight-line path.
When you roll a ball off the edge of a table, the component of velocity that doesn't change as it falls is the
the horizontal component (horizontal never changes)
Strange as it may seem, it is just as hard to accelerate a car on a level surface on the Moon as it is here on Earth. This is because
the mass of the car is independent of gravity.
The attraction of a person's body toward the Earth is called weight. The reaction to this force is
the person's body pulling on the Earth.
If the sun collapsed to a black hole, the Earth's gravitational attraction to it would be
the same
A ball is thrown upwards and returns to the same position. Compared with its original (initial) speed after release, its speed when it returns is about
the same.
Consider two waterfalls, one twice the height of the other. The kinetic energy of each kilogram of water falling to the bottom of the taller waterfall is about
twice as much
When a rock thrown straight upwards gets to the exact top of its path, its
velocity is zero and its acceleration is about 10 meters per second per second.
A dam is thicker at the bottom than at the top partly because
water pressure is greater with increasing depth.
Passengers in a high-flying jumbo jet feel their normal weight in flight, while passengers in the orbiting space shuttle do not. This is because passengers in the space shuttle are
without supporting force
The net force on any object in equilibrium is
zero.
