Q&A Hero

Q: The elevator accelerates upwards and is now moving at a constant speed. a. 150 lb c. 170 lb b. 160 lb d. none of the above

Q: The elevator is accelerating upwards at 2 ft/s2.a. 150 lb b. 160 lb c. 170 lbd. none of the above

Q: When a freely falling object reaches its terminal speed,a. it is still acceleratingb. its acceleration is zeroc. it is deceleratingd. its acceleration cannot be determined

Q: You roll a ball off a table and at the same time drop a second ball straight down from the edge of table. The second ball reaches the ground ____________ the first ball reaches the ground. a. before b. at the same time that c. after d. before or after, depending on the masses, e. cannot be determined

Q: A car moving at a constant speed goes around a curve of 400 ft radius and then goes around a second curve of 200 ft radius. The centripetal force acting on the car as it goes around the 200 ft radius curve is ___________ the value of the centripetal force acting on the car as it goes around the 400 ft radius curve. a. one quarter b. one half c. the same as d. twice e. four times

Q: Two identical cars are traveling around the same curve on a highway. One of them is moving at 60 mph, and the other is moving at 30 mph. The centripetal force acting on the car moving at 60 mph is __________ the value of the centripetal force acting on the car moving at 30 mph. a. one quarter b. one half c. the same as d. twice e. four times

Q: The frequency of a body oscillating from a spring on the moon is___________ the frequency of the same body oscillating from the same spring on earth. a. the same as b. larger than c. smaller than d. not related to e. depending on the mass, smaller or larger than

Q: If object A has more mass than object B, a. A will weigh more than B. b. A will be harder to accelerate than B. c. A will be harder to keep moving in a circle. d. all of the above

Q: You whirl a 2 kg body attached to a 1 meter cord around your head in a nearly horizontal circle with a speed of 4 m/s. The tension in the cord is a. 2 N b. 4 N c. 8 N d. 16 N e. 32 N

Q: Two forces of 4 N and 12 N act on a body simultaneously. The net force on the body is a. 4 N b. 12 N c. 16 N d. 8 N e. impossible to tell from the given information

Q: Starting from rest, a 2 kg body acquires a speed of 8 m/s in 2 seconds. The net force acting on the body is a. 2 N b. 4 N c. 8 N d. 16 N e. 6 N

Q: You push on a block on frictionless ice with a force of 8 N, causing it to accelerate at 2 m/s2. The mass of the block is a. 2 kg b. 4 kg c. 8 kg d. 16 kg e. 6 kg

Q: Which is larger, a newton or a pound? a. a newton b. a pound c. This question is nonsensethey don"t measure the same physical quantity. d. They are the same size.

Q: If the net force on an object is zero, a. there must be no forces acting on the object b. the object must be at rest c. the object's acceleration must be zero d. there can be no friction acting on the object

Q: The force that keeps your feet from sliding as you walk is a. centripetal force b. weight c. kinetic friction d. static friction e. none of the above

Q: The force needed to make an object move in a circle is a. centripetal force b. weight c. kinetic friction d. static friction e. none of the above

Q: The SI units of acceleration are a. mi/h b. km/h c. m/s d. m/s2 e. none of the above

Q: The SI units of velocity are a. mi/h b. km/h c. m/s2 d. m/s e. none of the above

Q: An example of an action at a distance force is a. tension b. weight c. static friction d. kinetic friction e. none of the above

Q: The acceleration of a body is a. always in the same direction as its velocity b. always in the same direction as the net force on the body c. in the direction that the body is moving d. equal to the net force on the body e. none of the above

Q: A ball on a string is being whirled around overhead when the string breaks. The ball will move in the direction of the centripetal force the moment the string breaks.

Q: A satellite orbiting the Earth in a circular orbit at 400 miles from the center of Earth is moved to a distance of 1,200 miles from the center of Earth. The gravitational force between the Earth and satellite changes by a factor of 3.

Q: An aircraft weighing 1,500 N has a mass of 153 kg..

Q: An aircraft weighing 1,500 N is accelerated at 15 m/s2 , the force acting on the aircraft is 2,295.9 N.

Q: As an artillery shell travels from the gun to the target, the projectile's vertical speed changes, but it's horizontal speed stays constant.

Q: Tides are caused because different parts of the earth's oceans are at different distances from the moon.

Q: Gravity acts over a limited distance range.

Q: As you go from a point where a gravitational field is strong to a point where the gravitational field gets weaker, the gravitational field lines get farther apart.

Q: The direction of a field line at a point in space shows the direction of the force that would act on a body placed at the point.

Q: Just above the surface of the earth, the direction of the gravitational field is away from the earth.

Q: Planetary orbits are circles.

Q: If a body were in orbit very near the surface of the earth, its centripetal acceleration would be equal to g.

Q: A body on the surface of the earth weighs 400 lb. The radius of the earth is about 4,000 miles. If this same body were placed on a 4,000 mile high tower, its weight would be 200 lb.

Q: As you go higher and higher above the surface of the earth, the mass of a body stays constant.

Q: A newton is larger than a pound.

Q: When you jump, you accelerate upward because the floor exerts an upward force on you.

Q: You push on a wall, and the wall pushes back on you with the same force. This is an example of Newton's third law.

Q: To hold a 5 lb bag of sugar in your hand, you must push upwards on it with a force of 5 lb. This is an example of Newton's third law.

Q: When a body moves in a straight line with increasing speed, the net force on it must be increasing.

Q: The displacement vector from the equilibrium position points up.

Q: The displacement vector from the equilibrium position has its largest magnitude.

Q: The velocity points down.

Q: The acceleration is zero.

Q: The net force points downward.

Q: The net force on the body has its largest magnitude.

Q: As an object moves faster through the air, its terminal speed increases.

Q: When an object reaches its terminal speed, its acceleration is zero.

Q: As a projectile moves its speed stays constant while its direction changes.

Q: At the peak of its motion, the acceleration of a projectile is zero.

Q: During its entire motion, the acceleration of a projectile is always g.

Q: You throw a ball straight up, it peaks out and then comes back down to you. During this motion, the velocity and acceleration always point in the same direction.

Q: When a body moves with uniform acceleration, the net force on it is zero.

Q: With a fixed force, you will impart the same acceleration to a body on the earth and on the moon.

Q: You roll a ball off a table and at the same time drop a second ball straight down from the edge of the table. The second ball reaches the ground before the first ball.

Q: When a car goes around a curve at twice the speed, the centripetal force on the car doubles.

Q: When a car goes around a curve of smaller and smaller radius, the centripetal force on it decreases.

Q: You are presently exerting a gravitational force on the earth.

Q: The weight of an object equals its mass times the acceleration of gravity.

Q: "Net force" means the vector sum of all the individual forces acting on a particular body.

Q: All forces have specific directions associated with them.

Q: A satellite orbits the earth at a distance of 10,000 miles from the earth's center. At this distance the force of gravity on the satellite is 90 lbs. (a) What would the force on the satellite be if the distance were 5,000 miles instead? (b) At what distance from the earth's center would the force on the same satellite be 10 lbs?

Q: A child on a merry-go-round is moving with speed 4 m/s in a circle with radius 2 m. If the child's mass is 30 kg, what is the centripetal force?

Q: A certain speed boat weighs 4,900 N. It can accelerate from 0 to 20 m/s in 5 seconds. (a) What is the mass of the boat? (b) What is the acceleration? (c) How large is the net force acting on the boat?

Q: A 3,000 kg truck experiences a net force of 2,000 N. What is its acceleration?

Q: A ball rolling down a hill has a constant acceleration of 3 m/s2. If the ball's mass is 2.5 kg, what is the net force acting on the ball?

Q: Find your own weight in newtons.

Q: A steel ball has a mass equal to 5 kilograms. What is the ball's weight?

Q: Match each item with the correct statement below.a. increases c. stays the sameb. decreases34/ As an astronaut is being launched into space, the astronaut's mass35/ As a rocket is being launched into space with a constant force (F), the acceleration36/ As the distance between two objects increases, the gravitational force37/ As the radius of turn being made by an aircraft increases, the centripetal acceleration on the aircraft

Q: Match each item with the correct statement below.a. zero net forceb. constant net force in the same direction as velocityc. constant net force opposite to velocityd. constant net force perpendicular to velocitye. net force decreasing with speedf. restoring force proportional to displacement26/ motion in a straight line with decreasing speed27/ motion in a straight line with increasing speed28/ motion in a straight line at constant speed29/ motion in a circle30/ a body reaching a terminal velocity31/ a body not moving32/ simple harmonic motion33/ a body falling through air

Q: Match each item with the correct statement below.a. m f. m/sb. m2 g. m/s2c. m3 h. Nd. s i. kge. Hz11/ the area of the sheet of paper you are looking at12/ the reading on your watch13/ the speedometer reading on your car14/ your weight15/ the mass of a baseball16/ the force exerted on a baseball by a baseball bat17/ the distance between your school and your home18/ the quantity describing how the speed of your car changes19/ the pitch of a note when a piano key is struck20/ the frequency of a body vibrating at the end of a spring21/ the volume of a 5 lb bag of sugar22/ air resistance23/ static and kinetic friction24/ the quantity that measures the resistance of an object to being accelerated25/ the gravitational pull of the earth on the moon

Q: Match each item with the correct statement below.a. centripetal force h. SIb. circle i. simple harmonic motionc. ellipse j. static frictiond. field k. terminal speede. kinetic friction l. tidesf. mass m. weightg. parabola1/ needed to make an object move in a circle2/ keeps our feet from sliding as we walk3/ keeps our feet from sliding as we walk4/ caused by the moon's gravitational pull5/ shape of the path of a projectile6/ air resistance is one example7/ the force of air resistance leads to this8/ the force of gravity acting on a body9/ an object hanging from a spring can do this10/ a measure of an object's resistance to acceleration

Q: An object is dropped from a tall building. The net force acting on the object is the difference between the object's _________ and the force of air resistance.

Q: A car and driver have a total mass of 945 kg. While rounding a curve on a flat road at a speed of 29 m/s, the net force acting on the car and driver is determined to be 56,767.5 N. The radius of the curve is__________.

Q: The sensitive dependence upon initial conditions of the evolution of some physical systems is a feature of __________.

Q: The major influence on the tides is due to __________.

Q: During the period of one day, the number of high tides at a given location is about __________.

Q: A body on the surface of the earth weighs 400 lb. The radius of the earth is about 4,000 miles. If this same body were placed on a 4,000 mile high tower, its weight would be __________.

Q: The shapes of planetary orbits are __________.

Q: As the radius of the orbit of an artificial satellite increases, its orbital period __________.

Q: As you go higher and higher above the surface of the earth, the acceleration of a freely falling body __________.