Physics Concept ?'s 2
Newton's law of gravity describes the gravitational force between
All of the above
Which of these objects is in equilibrium?
All of the above
Two coins rotate on a turntable. Coin B is twice as far from the axis as Coin A.
Angular velocity of A equals B
How many times per day does the International Space Station- or any satellite in a similar low orbit- go around the earth?
15
As an audio CD plays, the frequency at which the disk spins changes. At 210 rpm, the speed of a point on the outside edge of the disk is 1.3 m/s. At 420 rpm, the speed of a point on the outside edge is:
2.6 m/s
What does the scale read?
2000 N
A ring, seen from above, is pulled on by three forces. The ring is not moving. How big is the force F?
20sin N
The gravitational force between two asteroids is 1 million N. What will the force be if the distance between the asteroids is doubled?
250,000 N
The two masses are at rest. The pulleys are frictionless. The scale is in kg. The scale reads
5 kg
Two boxes are suspended from a rope over a pulley. Each box has weight 50 N. What is the tension in the rope?
50 N
Starting from rest, a wheel with constant angular acceleration spins up to 25 rpm in a time T. What will its angular velocity be after time 2T?
50rpm
This is the angular velocity graph of a wheel. How many revolutions does the wheel make in the first 4 seconds?
6
A 60 kg person stands on each of the following planets. On which planet is her weight the greatest?
A (Single R&M)
The restoring force of three springs is measured as they are stretched. Which spring has the largest spring constant?
A (Steepest slope)
A coin is rotating on a turntable; it moves without sliding. At the instant shown in the figure, which arrow gives the direction of the coin's velocity?
A (positive y coordinate)
A coin is rotating on a turntable; it moves without sliding. At the instant shown, suppose the frictional force disappeared. In what direction would the coin move?
A (positive y coordinate)
Hooke's law describes the force of
A spring
Boxes A and B are sliding to the right on a frictionless surface. Hand H is slowing them. Box A has a larger mass than Box B. Considering only the horizontal forces:
Fb on H=Fh on B GREATER Fa on b =Fb on a
The four forces shown have the same strength. Which force would be most effective in opening the door?
Force F1 (Force straight up by end of door)
When a car turns a corner on a level road, which force provides the necessary centripetal acceleration?
Friction
In general, the coefficient of static friction is
Greater than the coefficient of kinetic friction
You are riding in an elevator that is accelerating upward. Suppose you stand on a scale. The reading on the scale is:
Greater than your true weight
An object will be stable if:
Its center of gravity lies over its base of support
If you are performing the weightlifting exercise known as the strict curl, the tension in your biceps tendon is:
Larger than the weight you are lifting
An elevator is suspended from a cable. It is moving upward at a steady speed. Which is the correct free-body diagram for this situation?
Length between weight and tension equals. B
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:
Less than 490 N
A box with a weight of 100 N is at rest. It is then pulled by a 30 N horizontal force. Does the box move?
No
An old fashioned tire swing exerts a force on the branch and a torque about the point where the branch meets the trunk. If you hang the swing closer to the trunk, this will ___________ the force and ______________ the torque.
Not change, decrease
What factor does the torque on an object not depend on?
Object's angular velocity
A satellite orbits the Earth. A Space Shuttle crew is sent to boost the satellite into a higher orbit. Which of these quantities increases?
Period
An ice hockey puck is tied by a string to a stake in the ice. The puck is then swung in a circle. What force is producing the centripetal acceleration of the puck?
Tension in the string
The astronauts on the International Space Station are weightless because
They are in free fall
Two satellites have circular orbits with the same radius. Which has a higher speed?
They have the same speed
A ball at the end of a string is being swung in a horizontal circle. What is the direction of the acceleration of the ball?
Toward the center of the circle
A ball at the end of a string is being swung in a horizontal circle. What is the direction of the net force on the ball?
Toward the center of the circle
Rashid and Maria are riding a merry go round that is spinning steadily. Sofia is twice as far from the axis as is Rashid. Sofia's speed is __________ Rashid.
Twice
A car that's out of gas coasts over the top of a hill at a steady 20 m/s. Assume air resistance is negligible. Which free body diagram describes the car at this instant?
Up and down ( Net force downward) Bottom longer than top
A physics textbook swings back and forth as a pendulum. Which is the correct free body diagram when the book is at the bottom and moving to the right?
Up and down (Net Force upward) Top longer than bottom
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 half as far as bar A. Which has the larger value of Young's modulus Y?
Y(a) GREATER than Y(b)
A very ridged material- one that stretches or compresses only slightly under large forces- has a large value of
Young's modulus
A box on a rough surface is pulled by a horizontal rope with tension T. The box is not moving. In this situation:
fs= T
For uniform circular motion, the acceleration
is directed toward the center of the circle
The box is sitting on the floor of an elevator. The elevator is accelerating upward. The magnitude of the normal force on the box is
n greater than mg
A box is being pulled to the right at steady speed by a rope that angles upward. In this situation:
n less than mg
If an object is rotating clockwise, this corresponds to a __________ angular velocity.
negative
What are the components in the coordinate system shown?
wx= -w sin wy= -w cos
An object is in equilibrium if
Both A and B
Which object is in static equilibrium?
C (Long middle arrow, short arrow on top and bottom)
A coin sits on a turntable as the table steadily rotates counterclockwise. The free body diagrams below show the coin from behind, moving away from you. Which is correct?
C (straight up and down, r on the left x-axis)
A hollow tube lies flat on a table. A ball is shot through the tube. As the ball emerges from the other end, which path does it follow?
C (straight up)
All three 50 kg blocks are at rest. The tension in rope 2 is
Equal to the tension in rope 1
A 50 kg student (mg= 490 N) gets in a 1000 kg elevator at rest and stands on a metric bathroom scale. Sadly, the elevator cable breaks. What is the reading on the scale during the few seconds it takes the student to plunge to his doom?
0 N
Starting from rest, a wheel with constant angular acceleration turns through an angle of 25 rad in a time T. Through what angle will it have turned after time 2T?
100 rad
A passenger on a carnival ride rides in a car that spins in a horizontal circle as shown at the right. At the instant shown, which arrow gives the direction of the net force on one of the riders?
D (negative x coordinate side)
A coin is rotating on a turntable; it moves without sliding. At the instant shown in the figure, which arrow gives the direction of the frictional force on the coin?
D (negative x coordinate)
A softball pitcher is throwing a pitch. At the instant shown, the ball is moving in a circular arc at a steady speed. At this instant, the acceleration is
Directed right
A car turns a corner on a banked road. Which of the diagrams could be the car's free body diagram?
E ( Net force toward center, Static friction slightly downward)
A roller coaster car does a loop the loop. Which of the free body diagrams shows the forces on the car at the top of the loop? Rolling friction can be neglected.
E (pulley system free body diagram)
Which point could be the center of gravity of this L-shaped piece?
Point A (Point in middle of other two points on piece)
Which third force on the wheel, applied at Point P, will make the net torque zero?
Point A (Same line and direction as Point P)
The angular displacement of a rotating object is measured in:
Radians
A coin sits on a turntable as the table steadily rotates counterclockwise. What force or forces act in the plane of the turntable?
Static friction pointing inward
The top box is accelerated across a frictionless table by the falling mass m. The string is massless, and the pully is both massless and frictionless. The tension in the string is
T LESS than mg
Boxes A and B are being pulled to the right on a frictionless surface; the boxes are speeding up. Box A has a larger mass than Box B. How do the two tension forces compare?
T1 LESS than T2
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
A net torque applied to an object causes
The angular velocity of the object to change
A box is being pulled to the right over a rough surface. T is greater than fk, so the box is speeding up. Suddenly the rope breaks. What happens?
The box slows steadily until it stops
A ball at the end of a string is being swung in a horizontal circle. The ball is accelerating because:
The direction is changing
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
Consider the situation in the figure. Which pair of forces is an action/reaction pair?
The friction force acting on A and the friction force acting on B
Two identical satellites have different circular orbits. Which has a higher speed?
The one in the smaller orbit
Moment of inertia is:
The rotational equivalent of mass
Rashid and Maria are riding a merry go round that is spinning steadily. Sofia is twice as far from the axis as is Rashid. Sofia's angular velocity is _________ that of Rashid.
The same as
The force of Planet Y on Planet X is ___________ the magnitude of
the same as