physics 1 final

Two blocks of masses m1= 8 kg and m2= 4 kg are placed in contact with each other side-by-side (m1 on the left and m2 on the right) on a frictionless, horizontal surface. If a constant horizontal push of magnitude F = 60 N is applied to m1 directed to the right, which one of the following is correct?

Acceleration of the system is 5 m/s2, net force on m1 is 40 N and net force on m2 is 20 N.

consider the following three objects: A. A car driving down the road at a constant velocity. B. A block sitting at rest on a table. C. A skydiver falling at a constant velocity. Which of these objects is in equilibrium?

All these objects are in equilibrium.

Which of the following situations is impossible?

An object has constant non-zero acceleration and changing velocity.

A ball rolls around a circular track with an angular velocity of 6π rad/s. What is the period of the motion?

(1/3) s.

The time to go from 0 to 80 mph is 3.6 s for "2016 Chevy Corvette" and 9.0 s for "2016 Chevy Sonic". Which of the following is correct?

(Acceleration)_Corvette > (Acceleration)_Sonic.

You walk to the right at a constant rate, moving 6 m in 3 s. At t = 0 s, you pass the x = 1 m mark. What is your position at t = −1 s?

- 1 m

] Jenny is at position x = - 23 m. She then undergoes a displacement What is her final position?

- 73 m

A ball of mass m = 0.25 kg rolling to the right at 2.0 m/s strikes a wall and rebounds to the left at 1.0 m/s. What is the impulse delivered to it by the wall?

-0.75 kg-m/s

A 10-cm-long spring (spring constant = 500 N/m) is attached to a wall. When pulled horizontally with a force of 20 N, the spring stretches to a length of

14 cm

A force pushes a cart for 1 s to the right, starting from rest. To achieve the same speed with a force half as big, the force would need to push for

2.0 s

An audio CD plays so the frequency at which the disk spins changes from 210 rpm to 315 rpm. If the speed of a point on the outside edge of the disk is 1.50 m/s at 210 rpm, what's the speed of a point on the outside edge at 315 rpm?

2.25 m/s

Assuming that your mass is 45 kg and that g = 10 m/s2, how much gravitational potential energy do you gain when you climb a tree that is 5 m tall?

2250 joules

A Saturn V rocket is launched straight up with a constant acceleration of 18 m/s2. After 150 s, how fast is the rocket moving?

2700 m/s

A machine uses 1000 J of electric energy to raise a heavy mass, increasing its potential energy by 300 J. What is the efficiency of this process?

30%

A speedy seabird is at 43 miles east of its roost at 12:00 PM and 80 miles east of its roost at 12:30 PM. Given that 1 mile = 1609 m, 1 hr = 60 min and 1 min = 60 sec, the velocity of the seabird is approximately

33 m/s east of its roost.

A wheel, starting from rest and rotating with constant angular acceleration, turns through an angle of 16 rad in a time t. Through what angle will it have turned after time 0.5t?

4 rad

John ran up the hill at 7.0 m/s. If the horizontal component of his velocity vector was 5.1 m/s, the vertical component of his velocity was approximately

4.8 m/s

At a particular instant, a free-falling object has a speed of 30 m/s. Assuming a free-fall acceleration to be 10 m/s2, exactly 1 s later its speed will be

40 m/s.

Planet X has free-fall acceleration 8 m/s2 at the surface. Planet Y has twice the mass and twice the radius of planet X. On Planet Y,

4m/s2

A small wooden block is sliding down a 30-degree frictionless Assuming that g = 10 m/s2, the acceleration of the block down the incline is

5 m/s2

A ball rolls around a circular track so the period of the motion is 0.125 s. What is the angular velocity?

50.3 rad/s

The average speed of driving 30 miles in 1 hour is the same as the average speed of driving

60 miles in 2 hours.

A car A is moving at a constant velocity of 60 mph due north. Which of the following represents the velocity of a car B that is moving with the same velocity but in opposite direction?

60 mph due south

A massless spring hangs from the ceiling. How much does its potential energy increase, if a 28.8-kg mass is attached to it? The spring constant is 4800 N/m.

8.3 J m=28.8 kg g=9.8 m/s^2 W=mg =28.8*9.8 =282.24 N W=k*x x=282.24/4800 =0.0588 m potential energy=1/2kx^2 =0.5*4800*0.0588*0.0588 =8.29 j

A 50-kg student (mg = 490 N) gets in a 1000-kg elevator at rest and stands on a metric bathroom scale. As the elevator accelerates upward, the scale reads

> 490 N

Emma is pulling a wooden block with a force of 3 N to the east while Nick is simultaneously pulling the same block with a force of 4 N to the north. If Emily comes in and wants to apply a force simultaneously on the block so it does not move at all, which of the following is correct for the force she applies?

A force of 5 N at 53 degrees S of W

Which of the following is an example of uniform motion?

A hockey puck sliding in a straight line at a constant speed.

Which of the following is not correct regarding a position-versus-time graph?

A slower speed corresponds to a steeper slope of the position-versus-time graph.

In an acceleration-versus-time graph, which of the following can you obtain by calculating area under the curve?

Change in velocity.

Which of the following provides necessary centripetal force to a satellite orbiting earth in a circular orbit at a height h above earth's surface?

Gravitational force.

A box is sliding down an incline at constant speed. What energy transformation is taking place?

Gravitational potential energy -> Thermal energy

A steel beam hangs from a cable as a crane lifts the beam. What forces act on the beam?

Gravity and tension in the cable.

A bobsledder pushes her sled across horizontal snow to get it going, then jumps in. After she jumps in, the sled gradually slows to a halt. What forces act on the sled just after she's jumped in?

Gravity, a normal force, and kinetic friction

Which of the following provides necessary centripetal force to a car negotiating a banked road?

Horizontal component of normal force.

An object moving faster than the earth's escape velocity (about 11 km/s) has enough energy to escape the pull of the earth's gravity. Which of the following gas molecules would be most likely to be moving at a speed high enough to escape the earth's atmosphere?

Hydrogen

Which of the following quantities has the SI units of N-s?

Impulse

Choose the correct statement from the following:

In perfectly inelastic collision, momentum is conserved but colliding particles stick together.

A sample of nitrogen gas is inside a sealed container. The container is slowly compressed, while the temperature is kept constant. Which of the following thermodynamic processes best represents this situation?

Isothermal

What does a net torque applied to an object do?

It causes the angular velocity of the object to change.

Which of the following statements is NOT true?

It is possible for two vectors of different magnitudes to add to zero.

Two identical stones are dropped from a tall building, one after the other. Assume air resistance is negligible. While both stones are falling, what will happen to the vertical distance between them?

It will increase.

A child is on a playground swing so he is motionless at the highest point of his arc and has highest velocity at the lowest point of his arc. What energy transformation takes place as he swings from his lowest point to the highest point of his motion?

Kinetic energy -> Gravitational potential energy

You have two objects A and B. The object A undergoes a temperature change of 1-degree Fahrenheit (from 35 degrees Fahrenheit to 36 degrees Fahrenheit) while the object B undergoes a temperature change of 1-degree Celsius (from 35 degrees Celsius to 36 degrees Celsius). Which object undergoes a larger change of temperature?

Object B.

Consider three cases shown here: Case I: A 10-N force acting perpendicular to the displacement. Case II: A 6-N force acting at 60 degrees to the displacement. Case III: A 2-N force acting parallel to the displacement. If all three displacements are the same, which force does the most work?

The 6-N force.

A skydiver has reached terminal velocity—she now falls at a constant speed, so her acceleration is zero. Is there a net force on her? If so, what is the direction?

There is no net force.

Which contains more molecules, a mole of hydrogen gas or a mole of oxygen gas?

They each contain the same number of molecules.

You awake in the night to find that your living room is on fire. Your one chance to save yourself is to throw something that will hit the back of your bedroom door and close it, giving you a few seconds to escape out the window. You happen to have both a sticky ball of clay and a super-bouncy Superball next to your bed, both the same size and same mass. You've only time to throw one. Which will it be? Your life depends on making the right choice!

Throw the Superball.

Which of the following pairs has the same SI units?

Torque and Work.

What are scalars and vectors?

Vectors have both magnitude and direction, but scalars only have magnitude.

What is the difference between speed and velocity?

Velocity contains information about the direction of motion while speed does not.

55-kg person stands on each of the following three planets and measures her weight as WA, WB and WC on the planet A, B and C respectively. Planet A: Mass 3M and Radius 3R. Planet B: Mass 2M and Radius 2R. Planet C: Mass M and Radius R. Which one of the following is correct?

WA < WB < WC

If you are standing on the floor, motionless, what are the forces that act on you?

Weight force and normal force.

Which of the following is NOT true?

Weight of an object does not change but its mass changes.

Which of the following best represents how we determine significant figures?

When multiplying and dividing quantities, we leave as many significant figures in the answer as there are in the quantity with the least number of significant figures.

Which of the following quantities is not a vector?

Work

Bars A and B are attached to a wall on the left and pulled with equal forces to the right. Bar B, with twice the radius, is stretched one-fourth as far as bar A. Which of the following is correct for Young's modulus Y?

YA = YB

Which of the following is NOT correct?

Zero acceleration means zero velocity.

A car is moving at 15 m/s to the right on x-axis. What is the y-component of its velocity?

Zero.

A ball has been tossed straight up. Ignoring air resistance, the free-body diagram just after the ball has left the hand contains

a downward force only.

Two metal balls are the same size but one weighs twice as much as the other. The balls are dropped from the roof of a single-story building at the same instant of time. If you ignore air resistance, the time it takes the balls to reach the ground below will be:

about the same for both balls.

An action/reaction pair of forces

acts on two different objects.

For a given banking angle of a curved road, the speed a car can take at the curve without assistance from friction increases with

an increase in the radius of curvature of the road.

For a given mass and shape of an object, the moment of inertia depends on

axis of rotation about which the object is rotated.

You pour a small glass of water at 20 degrees Celsius into a super-insulated large glass of water at 0 degree Celsius, and the container is sealed. An hour later, it is possible that the temperature of the mixture is

between 0 degree Celsius and 20 degrees Celsius.

If you do not want to bank a curved level road, the maximum speed of a car you are driving on the curved level road of fixed radius of curvature without sliding depends on the

coefficient of static friction.

A heavy metal cart and a light plastic cart are both pushed with the same force for 1.0 s, starting from rest. After the force is removed, the momentum of the light plastic cart is

equal to that of the heavy metal cart.

10-year-old Jenny stands on a skateboard. Her older brother John starts pushing her backward and she starts speeding up. The force of John on Jenny is

equal to the force of Jenny on John.

A falling object reaches terminal speed when the drag force is

exactly equal to the weight of the object.

A ball is thrown vertically upward and then comes back down. During the ball's flight up and down, its velocity and acceleration vectors are

first in opposite directions and then in the same direction.

In general, the coefficient of static friction is

greater than the coefficient of kinetic friction.

When water evaporates into steam,

heat is absorbed by the water.

Velocity vectors point

in the same direction as displacement vectors.

For uniform circular motion, the acceleration

is directed toward the center of the circle.

A car is slowing down to the right on a straight road. The sign of the acceleration

is negative.

A car is slowing down to the left on a straight road. The sign of the acceleration

is positive.

If an object is speeding up,

its acceleration can be positive or negative depending on the direction of motion.

If a fan blade is rotating clockwise and speeding up,

its angular velocity and angular acceleration both are negative.

An object's motion is uniform if and only if

its position-versus-time graph is a straight line.

The restoring force of three springs is measured as they are stretched. The plot of the force versus extension shows that the slope for the three springs follow SA > SB> SC. Which of the following is correct for the spring constants kA, kB and kC?

kA > kB > kC

The moment of inertia of an object is the rotational analog of

mass of the object in linear motion.

The fundamental physical quantities are

mass, length, time, temperature, amount of a substance, current, and luminous intensity.

To convert a physical quantity from g/cm3 to kg/m3, one must

multiply by 1000.

To convert a quantity from m/s to km/h, you must

multiply by 3600 and divide by 1000.

A box is being pulled to the right at steady speed by a rope that angles 30 degrees above the positive x-axis. In this situation, the relation between the normal force and the weight of the box is

n < m

which of the following pairs correctly and respectively correspond to the blank spaces in "Work is ----- when energy is transferred ----- of the system"?

negative, out

A ball is tossed straight up in the air. At its very highest point, the ball's instantaneous acceleration ay is

negative.

If a ball is tossed straight up in the air, the ball's acceleration at its very highest point is

negative.

The spring constant has units of

newtons per meter.

The slope at a point on a position-versus-time graph of an object is the

object's instantaneous velocity at that point.

Kevin is riding a merry-go-round with a radius of 5 m at a constant speed of 5 m/s. If his speed is halved, the centripetal force on him will be

one-fourth

If John walks 100 m to the right, then 50 m to the left, his net displacement vector

points to the right

If Jane walks 100 m to the left, then 200 m to the right, his net displacement vector

points to the right.

Which of the following pairs correctly and respectively correspond to the blank spaces in "Work is ----- when energy is transferred ----- the system"?

positive, into

Velocity and acceleration are actually

rates but for different quantities.

A box is being pulled to the right over a rough surface by means of a rope that is under a tension for T which is greater than the force of kinetic friction so the box is speeding up. If suddenly the rope breaks, the box

slows steadily until it stops.

If a particle A has twice the kinetic energy and half the mass of a particle B, the velocity of the particle A must be

twice that of the particle B.

If you are not wearing a seat belt and the car you are driving hits a fixed barrier, you will hit the steering wheel with some force. This is because

you continue moving even after the car has stopped.

A vector is directed 45 degrees south of east. What can you say about its horizontal and vertical components?

Both components are equal in magnitude but they both are negative.

You have two objects A and B. The object A undergoes a temperature change of 1-degree Celsius (from 35 degrees Celsius to 36 degrees Celsius) while the object B undergoes a temperature change of 1-degree Kelvin (from 35 degrees Kelvin to 36 degrees Kelvin). Which object undergoes a larger change of temperature?

Both objects undergo the same change of temperature.

If two components of a vector are Ax = - 3 cm and Ay = - 1 cm, which of the following is correct?

The vector must be directed at 60 degrees W of S.

Astronauts on the International Space Station are weightless because

they are in free fall.

Sarah is at position x = -50 m. She then undergoes a displacement of 50 m. What is her final position?

0 m

Sarah walks to the right at a constant rate, moving 3 m in 3 s. At t = 0 s, she passes the x = 1 m mark. What is her position at t = −1 s?

0 m

What is the frequency of a geostationary satellite (that appears to remain stationary as the earth rotates)?

0.0000116 revolutions per second.

A 30-g ball is fired from a 1.2 kg spring-loaded toy rifle with a speed of 15 m/s. What is the recoil speed of the rifle?

0.375 m/s

A turbine draws 100 J of thermal energy to turn a generator that produces 40 J of electrical energy while 60 J of thermal energy is exhausted into the environment. Which of the following represents the efficiency of the turbine?

0.4

11. A 3-meter long board weighing 50 N extends out over the edge of a table, with 40% of the board's length off the table. How far beyond the table edge can a 25-N cat walk before the board begins to tilt?

0.4 m

An object, when pushed with a net force F, has an acceleration of 2 m/s2. Now the same force is applied to an object that has four times the mass. Its acceleration will be

0.5 m/s2

A position-versus-time graph of an object's motion is a straight line at 45 degrees angle with the horizontal axis in the 1st What's the velocity of the object?

1 m/s

The gravitational force between two asteroids is 2,000,000 N. What will the force be if the distance between the asteroids is doubled?

1,000,000 N

A car pulls away from a stop sign with a constant acceleration. After traveling 5 m, its speed is 10 m/s. What will its speed be after traveling 45 m?

10 m/s.

A heat engine is working between a source at 90 degrees Celsius and a sink at 0 degree Celsius. What is the highest possible efficiency of this engine?

100 percent

Which of the following quantities is represented by the area under a velocity-versus-time graph of an object?

Displacement

Which of the following quantity is a vector?

Displacement

What happens to the entropy of an isolated system?

Either increases or remains constant.

Which of the following is correct?

Power is a scalar quantity; its unit is the watt where 1 W = 1 J/s.

The defining equation for calorimetry is

Q1 + Q2 = 0

What is the angular displacement of a rotating object measured in?

Radians.

Which type of heat transfer can happen through empty space?

Radiation

Starting from rest, a small marble first rolls down a steeper hill, then down a less steep hill of the same height. For which is it going slower at the bottom?

Same speed at the bottom of both hills.

A skydiver has reached terminal velocity—she now falls at a constant speed, so her acceleration is zero. Is there a net force on her before she reaches terminal velocity?

Since it's a freefall, the force of gravity is the only force on her directed downward

Which of the following is correct?

Speed is scalar, but velocity and acceleration are vectors.

Which of the following forces provides necessary centripetal force to a car negotiating an unbanked level road?

Static friction force.

A ball at the end of a string is being swung in a horizontal circle. What force is producing the centripetal acceleration of the ball?

Tension in the string

The conservation of angular momentum requires that if no net torque acts on an object that is rotating about an axis,

The angular velocity of the object must remain constant regardless of whether its moment of inertia suddenly decreases or increases.

The drag force pushes opposite your motion as you ride a bicycle. If you reduce your speed to one-half, what happens to the magnitude of the drag force?

The drag force decreases.

The drag force pushes opposite your motion as you ride a bicycle. If you double your speed, what happens to the magnitude of the drag force?

The drag force increases.

Which of the following is correct?

The elastic limit is the end of the elastic region.

A coin sits on a turntable that steadily rotates counterclockwise. What force or forces act in the plane of the turntable?

The force of static friction (that provides necessary centripetal force) towards the center of the table.

Which of the following is true?

The magnitude of a vector cannot be smaller than the magnitude of any of its components.

If the kinetic energy of an object quadruples, what happens to the momentum?

The momentum is doubled.

Which of the following is (are) true about entropy?

The most efficient possible heat engine is the one that has zero change in entropy. The entropy quantifies the spread or dispersal of thermal energy. The entropy of a system is maximum when the system is in equilibrium.

A camper first walks 1 km northeast from his car and then walks 1 km south, at which point he discovers a tower. Which of the following is correct about his net displacement?

The net displacement must be at an angle south of east.

For an extended object to be in static equilibrium,

The net force on the object must be zero, and the net torque on the object must also be zero.

Two identical satellites A and B have different circular orbits of radii rA (smaller) and rB (larger) respectively. Which satellite has a lower speed?

The satellite B.

A kilogram ball and a pound ball are dropped from a height of 10 feet at the same time. Given that 1 lb = 2.2 kg, which of the following is correct in the absence of air resistance?

The two balls end in a tie.

When other forms of energy are transformed into thermal energy,

the change is irreversible, the energy isn't lost, but the opportunity to use the energy is lost.

The area under a velocity-versus-time graph of an object is

the displacement of the object.

John and Ken are riding a merry-go-round that is spinning steadily. John is twice as far from the axis as is Ken. John's angular velocity is

the same as that of Ken.

A 2-kg iron ball and a 5-kg iron ball are dropped from rest from the same height. Neglecting air resistance, the acceleration of the heavier ball will be

the same.

A truck collides head-on with a small compact car. During the collision:

the truck exerts the same amount of force on the car as the car exerts on the truck