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physic problems

problems

final!

PHYSICS FINAL

• how does the weight of a falling body compare with the air resistance it encounters before i reaches terminal velocity.
• the weight of the falling body is greater than air resistance
• how does the weight of a falling body compare with the air resistance itencounters after it reaches terminal velocity?
•  the weight of the falling  body is equal to air resistance
• why is it that a cat falls from the top of a 50 story building wil hit the ground no faster than if it fell from a 20th story?
• the terminal velocity attained by the falling cat is the same whether it falls from 50 stories or 20 stories.  once terminal velocity is reached, falling extra distance does not effect the speed . (the low terminal velocities of small creatures enables them to fall without harm from heights that would kill larger creatures.)
• a jumbo jet has a mass of 100,000 kg. the thrust for each of four engines is 50,000 N. what is the jet's acceleration in meters per second when taking off.
• 2
• a girl pulls on a 10kg wagon with a constant force of 30 N. what is the wagon's acceleration in meters per second per second?
• 3
• an apple weighs 1N.  the magnitude of net force on the apple when it is in free fall is
• 1 N
• careful:  on thesurface of jupiter, where the acceleration is due to gravity is about three times that of earth, a 100-kg rock would have a mass of about
• 100kg
• a 10-M falling object encounters 4 N of air resistance.  The magnitude of the net force on the object is
• 6 N
• your weight is
• the gravitational attraction between you and the earth
• in a deep dive,  a whale is appreciabl compressed by the pressure of the sirrounding water.  What happens to the winter's density?
• its density increases
• what is the weight of a cubic meter of cork? (density of cork- 300 kg/m^3)
• 3000 N  could you lift it?
• no
• when an ice cube in a glass of water melts, does the water level in the glass rise, fall, or remain unchanged?
• the water level at the side of the glass is unchanged
• what if the ice cube has many bubble
• he water level at the side of the glass is unchanged
• how about if the ice cube contains many grains of heavy sand?
• the water level at the side of the glass will fall slightly
• a dike in holland springs a leak through a hole of area 1 cm^3 at a depth of 1 m below the water surface.  with what force would a boy have to push on the hole with his thumb to stop the leak?
• 1 N could he do it?
• yes
• one liter of water has a mass of
• 1 kg
• a rock suspended by a weighing scale weighs 5 N out of water and 3 N when submerged in water.  what is the buoyant force of the  rock?
• 2 N
• which has more volume- a kilogram of gold or a kilogram of aluminum?
• 1 kg  of aluminum has more volume
• which has more weight-- a liter of ice or a liter of water?
• a liter of water weighs more than a liter of ice
• the current through two identical light bulbs connected in series is 0.25 A.  The voltage across both bulbs is 110 V.  The resistance of a single light bulb is
• 220 ohms
• which statement is correct?
• current flows through a circuit
• an ampere is a unit of electrcal
• current
• the current through two identical light bulbs connected in a series is 0.2A.  the voltage across both bubls is 110 V.  the resistance of a single light bulb is
• 220 ohms
• A 4 ohms resistor is connected in parallel with a 6 ohm resistor.  the combination roduces an equivalent resistance of
• 2.4 ohms
• when a light switch is turned on in a dc circuit, the average speed of electrons in the lamp is
• less than 1 cm/s.
• the current through a 10 ohm resistor connected to a 120-V power supply is
• 12 A.
• An ampere is a unit of electrical 
• current
• two charges separated by 1 m expert a 1-N force on each other.  If the magnitude of each charge is doubled, the force on each charge is 
• 4 N
• two charges separated by 1 m exert a 1-N force on each other.  If the charges are pulled to a 3-m separation distance, the force on each charge will be
• 0.11 N.
• show below is part of the magnetic field of "horseshoe" magnet.  An electron is shot from the right, toward a spot just between the ends of the magnet. the electron
• is deflected into the plane of the page
•  

Physics 1050 Test 1

-if air resistance is negligible, which ball will have the greater speed when it strikes the ground below?
--both will strike the ground below at the same time

-which of the following has the largest momentum relative to earth?
--a pickup truck speeding along the highway

-a rifle recoils from a firing bullet. the speed of the rifle is small because
--rifle has more mass than the bullet

-when a rifle is fired, it recoils so both the bullet and the rifle are set in motion. the rifle and bullet ideally acquire equal
--but opposite amounts of momentum

-a rifle has a mass of 2kg is suspended by strings. the rifle fores a bullet of mass 1/100 kg at a speed of 200m/s. the recoil velocity of the rifle is about
--1 m/s

-a 30 kg girl and a 25 kg voy face each other on friction-free roller blades. the girl pushes the boy, who moves away at a speed of 1.0 m/s. the girl's speed is
--0.83 m/s

-a 5000 kg freight car runs into a 10,000 kg freight car at rest. the couple upon collision and move with a speed of 2 m/s. what was the initial speed of the 5000 kg car?
--6 m/s

-a car moves 4 times as fast as another identical car. compared to the slower car, the faster car has
--16 times the KE

-a TV set is pushed a distance of 2 m with a force of 20 N that is in the same direction as the set moves. how much work is done on the set>
--40J

-when a car is braked to a stop, its kinetic energy is transformed to
--heat

-a 1000 kg and a 2000 kg car are hoisted the same distance in a gas station. raising the more massive car requires
--twice as much work

-when an object is lifted 10 m, it gains a certain amount of potential energy. if the same object is lifted 20 m, its potential energy gain is
--twice as much

-if you push an object twice as far while applying the same force, you do
--twice as much work

-a person on the edge of a roof throws a ball downward. it strikes the ground with 100 J of kinetic energy.  the person throws another identical ball upward with the same initial speed, and this too falls to the ground. neglecting air resistance, the second ball hits the ground with a kinetic energy of
--100 J

-a 51 kg diver steps off a diving board that is 10 m above the water. the diver hits the water with kinetic energy of
--5000 J

-does the KW of a car charge more when it goes from 10 to 20 km/h or when it goes from 20 to 30 km/h?
--the KE changes more from 20 to 30 km/h