Honors Physics Day 1 MC

In the Atwood machine shown in Fig. 4-1, if M= 0.60 kg and m= .40 kg, what is the magnitude of the acceleration of the system? (Ignore friction and the mass of the pulley.)

2.0 m/s2

What is the mass of an object what weighs 250 N in the surface of the Earth where the acceleration due to gravity is 9.8 m/s2?

25.5 kg

A person on a scale rides in an elevator. If the mass of the person is 60.0 kg and the elevator accelerates downward with an acceleration of 4.9 m/s2, what is the reading on the scale?

294 N

A girl pulls on a 10-kg wagon with a constant horizontal force of 30 N. If there are no other horizontal forces, what is the wagons acceleration in meters per second per second

3.0

A golf club hits a golf ball with a force of 2400 N. The golf ball hits the club with a force of

Exactly 2400 N

In Fig. 4-1 the scale at left is attached to the ceiling and a mass of 1.00 kg hangs from it. It reads 9.81 N. The identical scams at the right is connected by perfect strings passing over perfect pulleys to two 1.00 kg masses hanging vertically at the end of the strings. The scale at right reads

Exactly 9.81 N

Your bat hits the ball pitched to you with a 1500-N instantaneous force. The ball hits the bat with an instantaneous force, whose magnitude is

Exactly equal to 1500 N

An object of mass m is hanging by a string from the ceiling of an elevator. The elevator is moving up at a constant speed. What is the tension in the string

Exactly mg

In the absence of an external force, a moving object will

Move with constant velocity

In the absence of an external force, a moving object will

Move with constant velocity in a straight line

Compared to the mass of a certain object on Earth, the mass of the same object on the moon is

The same

A block of mass M slides down a frictionless plane inclined at an angleθ with the horizontal. The gravitational force is directed

Toward the center of the Earth

An object is propelled along a straight-line path by a force. If the net force were doubled, the object's acceleration would be

Twice as much

Two identical masses are attached by a light string that passes over a small pulley, as shown in Fig. 4-5. The table and the pulley are frictionless. The masses are moving

With an acceleration less than g

In Fig. 5-1, the block of mass is at rest on an inclined plane that makes an angleθ with the horizontal. The force of static friction must be such that

f= mg sinθ

Which of the following free-body diagrams best represent the free-diagram, with correct relative force magnitudes, of a person in an elevator that is traveling upward with a downward acceleration less then g? Ff is the force of the floor on the person and Fg is the force of gravity on the person.

B

Object A weighs 40 N in Earth, and object B weighs 40 N on the Moon. The Moon's gravity is one sixth of Earth's. Compare the masses of the objects

B has 6 times the mass of A

Which of the following free-body diagrams best represent the free-diagram, with correct relative force magnitudes, of a person in an elevator that is traveling upward with a constant velocity? Ff is the force of the floor on the person and Fg is the force of gravity on the person.

C

A constant net force acts on an object. Describe the motion of the object

Constant acceleration

Action reaction forces are

Equal in magnitude but point in opposite directions

Starting from rest, a 4.0-kg body reaches a speed of 8.0 m/s in 2.0 s. What is the net force acting on the body?

16 N

A stone is thrown straight up. At the top of its path, the net force in it is

Equal to its weight

A traffic light of weight 100 N is supported by two ropes as shown in Fig. 4-2. What are the tensions in the ropes?

83 N

A person on a scale rides in an elevator. If the mass of the person is 60.0 kg and the elevator accelerates upward with an acceleration of 4.90 m/s2, what is the reading on the scale?

882 N

A packing crate slides down an inclined ramp at a constant velocity. Thus we can deduce that

A frictional force is acting on it

Two boxes are connected by a cord running over a pulley as shown in Fig. 4-5. Box 1 of mass 8.0 kg rest on the top of the table; the coefficient of kinetic friction between box 1 and the table is .10. Box 2 has a mass of 15.0 kg. A. Draw the free-body diagrams for the 2 boxes, identifying all of the forces acting on each of the masses. B. Calculate the acceleration of the system. C. Calculate the tension in the chord

A. Box one is acted on by the force of gravity in a downward direction, the normal force due to the table top in an upward direction, the tension in the string toward the right, and the force of friction due to the table top toward the left. Box two is after on by the force of gravity in a downward direction and the tension in the string in an upward direction. B. 6.1 m/s2 C. 56 N

A heavy block at rest is suspended by a vertical rope. When the block is accelerated upward by the rope, the rope tension

Increases

If one object has twice as much mass as another object, it also has twice as much

Inertia

An object of mass m is hanging by a string from the ceiling of an elevator. The elevator is moving upward, but slowing down. What is the tension in the string?

Less than mg

A kilogram is a measure of an object's

Mass

A block of mass M slides down a frictionless plane inclines at an angleθ with the horizontal. The normal reaction force exerted by the plane on the block is

Mg cosθ

The maximum acceleration of a car while towing a second car twice its mass, compared to its acceleration with no car in tow, is

One third

A block of mass M slides down a frictionless plane inclined at an angleθ with the horizontal. The normal reaction reaction force exerted by the plane on the block is directed

Perpendicular to the plane

As a car drives with its tires rolling freely without any slippage, the type of friction acting between the tires and the road is

Static friction

A 20-N weight and a 5.0-N weight are dropped simultaneously from the same height. If if's air resistance. Compare their accelerations

The both accelerate at the same rate because they have the same weight to mass ratio

A book rests on a level table top. Which force does Newton's third law imply is equal in magnitude but opposite in direction to the weight of the book?

The force of the book on the Earth

Your weight is

The gravitational attraction force between you and the Earth

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 the Earth. This is because

The mass of the car is independent of gravity

A net force F accelerates a mass m with an acceleration a. If the same net force is applied to mass2m, then the acceleration will be

a/2

It's more difficult to start moving a heavy carton from rest than it is to keep pushing it with constant velocity, because

μk < μs