physics final

A child moving at constant velocity carries a 2 N ice-cream cone 1 m across a level surface. What is the net work done on the ice-cream cone? a. 0 J c. 2 J b. 0.5 J d. 20 J

a. 0 J

Which of the following is true of inertia? a. It is described in Newton's first law of motion. b. It is a property of motion. c. It is measured by weight. d. all of the above

a. It is described in Newton's first law of motion.

Why doesn't the principle of mechanical energy conservation hold in situations when frictional forces are present? a. Kinetic energy is not completely converted to a form of potential energy. b. Potential energy is completely converted to a form of gravitational energy. c. Chemical energy is not completely converted to electrical energy. d. Kinetic energy is completely converted to a form of gravitational energy.

a. Kinetic energy is not completely converted to a form of potential energy.

If friction is the only force acting on an object during a given physical process, which of the following assumptions can be made in regard to the object's kinetic energy? a. The kinetic energy decreases. b. The kinetic energy increases. c. The kinetic energy remains constant. d. The kinetic energy decreases and then increases.

a. The kinetic energy decreases.

In a coordinate system, the magnitude of the x component of a vector and θ, the angle between the vector and x-axis, are known. The magnitude of the vector equals the x component a. divided by the cosine of θ. b. divided by the sine of θ. c. multiplied by the cosine of θ. d. multiplied by the sine of θ. d. multiplied by the sine of θ.

a. divided by the cosine of θ.

A worker does 25 J of work lifting a bucket, then sets the bucket back down in the same place. What is the total net work done on the bucket? a. −25 J c. 25 J b. 0 J d. 50 J

b. 0 J

A jet moving at 500.0 km/h due east is in a region where the wind is moving at 120.0 km/h in a direction 30.00° north of east. What is the speed of the aircraft relative to the ground? a. 620.2 km/h b. 606.9 km/h c. 588.7 km/h d. 511.3 km/h

b. 606.9 km/h

What is the potential energy of a 1.0 kg mass 1.0 m above the ground? a. 1.0 J c. 10 J b. 9.8 J d. 96 J

b. 9.8 J

A batter strikes a baseball with a bat. Identify an action-reaction pair and describe the forces exerted by each. a. The batter exerts a force on the bat; the ball exerts a force on the bat. b. The batter exerts a force on the bat; the bat exerts a force on the batter. c. The bat exerts a force on the batter; the bat exerts a force on the ball. d. The ball exerts a force on the bat; the bat exerts a force on the batter.

b. The batter exerts a force on the bat; the bat exerts a force on the batter.

When a car's velocity is negative and its acceleration is negative, what is happening to the car's motion? a. The car slows down. b. The car speeds up. c. The car travels at constant speed. d. The car remains at rest. d. The car remains at rest.

b. The car speeds up.

A plank is inclined at angle θ, north of west. The direction of the normal force exerted by that plank on an object would be oriented at angle θ, a. north of west. b. east of north. c. south of east. d. west of south.

b. east of north.

A student holds a 6-N block of wood from a spring balance in an express elevator that maintains constant velocity traveling between floors. A spring scale reading of 5.9 N indicates that the elevator is a. starting an ascending trip. b. ending an ascending trip. c. ending a descending trip. d. traveling between floors.

b. ending an ascending trip.

Units that measure weight are units of a. acceleration. b. force. c. mass. d. velocity.

b. force.

Two dogs are tugging on a toy. One dog pulls with a horizontal force of 14 N due north. The other is pulling due east with a horizontal force of 14 N. What is the direction of the net external horizontal force on the toy? a. north b. northeast c. west d. northwest

b. northeast

If the sign of work is negative, a. the displacement is perpendicular to the force. b. the displacement is in the direction opposite the force. c. the displacement is in the same direction as the force. d. no work is done.

b. the displacement is in the direction opposite the force.

What is the kinetic energy of a 0.135 kg baseball thrown at 40.0 m/s? a. 54.0J c. 108J b. 87.0J d. 216J

c. 108J

A 3.00 kg toy falls from a height of 1.00 m. What will the kinetic energy of the toy be just before the toy hits the ground? (Assume no air resistance and that g = 9.81 m/s2.) a. 98.0 J c. 29.4 J b. 0.98J d. 294J

c. 29.4 J

What is the average power supplied by a 60.0 kg person running up a flight of stairs a vertical distance of 4.0 m in 4.2 s? a. 57 W c. 560 W b. 240W d. 670W

c. 560 W

A boat travels directly across a river that has a downstream current, v. What is true about the perpendicular components of the boat's velocity? a. One component equals v; the other component equals zero. b. One component is perpendicular to v; the other component equals v. c. One component is perpendicular to v; the other component equals −v. d. One component is perpendicular to v; the other component equals zero.

c. One component is perpendicular to v; the other component equals −v.

A truck and a car uniformly accelerate from rest to a velocity of 3.0 m/s in equal time intervals. The truck is ten times as massive as the car. Which of the following statements is correct? a. The acceleration of the truck is 1/10 that of the car. b. The truck travels 1/10 the distance of the car. c. The force on the truck is 10 times the force on the car. d. all of the above

c. The force on the truck is 10 times the force on the car.

For an object in contact with a given surface, the kinetic friction acting on the object a. usually is more than static friction. b. is independent of the normal force. c. depends on the composition and qualities of the surfaces in contact. d. acts perpendicular to the surface.

c. depends on the composition and qualities of the surfaces in contact.

The change in the horizontal velocity of a 12-kg scooter is +0.5 m/s. What is the net horizontal force acting on it? a. +24 N b. +6.0 N c. greater than 0 N d. 0 N

c. greater than 0 N

An object is at rest on an incline. The component of gravity acting downward and along the incline on the object is described as Fg, x = +8.0 N. Which axis is pointing up the incline? a. +x-axis b. +y-axis c. −x-axis d. −y-axis

c. −x-axis

Find the resultant of these two vectors: 2.00 × 102 units due east and 4.00 × 102 units 30.0° north of west. a. 300 units 29.8° north of west b. 581 units 20.1° north of east c. 546 units 59.3° north of west d. 248 units 53.9° north of west

d. 248 units 53.9° north of west

If both the mass and the velocity of a ball were tripled, the kinetic energy of the ball would increase by a factor of a. 3. c. 9. b. 6. d. 27.

d. 27.

Two books are lying next to each other on a library table. The force due to gravity on the first book is 9 N and on the second is 13 N. The gravitational force on the table itself is 125 N. The floor supports the table with an upward force of 147 N. In a free-body diagram of the table, how many contact forces and how many field forces should be represented? a. 1, 2 b. 1, 3 c. 2, 2 d. 3, 1

d. 3, 1

A force of 5 N and a force of 15 N acting on an object can produce the following net forces except a. 20N. c. 10N. b. 15 N. d. 5 N.

d. 5 N.

During a three-part circus stunt, a clown holds a ball. The clown then tosses the ball upward. After releasing it, the ball is caught a few moments later from above by another clown on a trapeze. Which set of data could represent the normal force exerted by the ground on the first clown during the stunt? The force due to gravity on the clown is 680 N and that on the ball is 20 N. a. 700N,695N,720N b. 700N,695N,700N c. 700N,705N,700N d. 700N,705N,680N

d. 700N,705N,680N

For which of the following situations is the conservation of mechanical energy most likely to be a valid assumption? a. A skateboard rolls across a sewer grate. b. A parachutist falls from a plane. c. You rub your hands together to keep warm. d. A soccer ball flies through the air.

d. A soccer ball flies through the air.

All of the following statements about kinetic friction are true except a. Kinetic friction is calculated by the equation Ff = μκ F n. b. Kinetic friction is exerted parallel to the surface. c. Kinetic friction is exerted opposite the direction of motion d. For an object on an incline, kinetic friction increases as the angle the incline above the horizontal increases.

d. For an object on an incline, kinetic friction increases as the angle the incline above the horizontal increases.

Which of the following statements are true about the concept of field forces? I. Fieldforcescanbeexertedbyobjectsthatareinphysicalcontact. II. Field forces can be exerted by objects that are not in contact. III. There are four fundamental field forces. a. I only b. II only c. II and III d. I, II, and III

d. I, II, and III

Which of the following statements describe an object in equilibrium? I. Theobjectisatrest. II. The object is moving at constant velocity. III. The net external force on the object is zero. a. I and II b. I and III c. II and III d. I, II, and III

d. I, II, and III

Which of the following statements are true about Fs, max in the equation μs = (Fs,max/Fn)? I. Fs, max is exerted perpendicular to the surfaces in contact. II. Fs, max represents the maximum value of the force of static friction. III. On a level surface, the magnitude of Fs, max equals the magnitude of the applied force that starts the object moving. a. I only b. II only c. I, II, and III d. II and III

d. II and III

A force unit is defined as the product of a mass unit and a unit of a. time. b. displacement. c. velocity. d. acceleration.

d. acceleration.

In an action-reaction pair, the a. action force is exerted first. b. action force and the reaction force are equal in magnitude and act in the same direction. c. action force and the reaction force are contact forces only. d. action force and the reaction force act on two different objects.

d. action force and the reaction force act on two different objects.

The normal force a. equals Fg in magnitude. b. points vertically upward. c. is a scalar quantity. d. acts perpendicular to a surface.

d. acts perpendicular to a surface.

The equation for determining gravitational potential energy is PEg = mgh. Which factor(s) in this equation is (are) not intrinsic to an object? a. m c. h b. g d. both g and h

d. bothgandh

The coefficient of kinetic friction a. is a type of contact force. b. is measured in newtons. c. depends on the normal force. d. depends on the composition and qualities of the surfaces in contact.

d. depends on the composition and qualities of the surfaces in contact.