Unit 8
What does the scale read? 500 N 1000 N 2000 N 4000 N
2000 N
Hooke's law describes the force of Gravity. A spring. Collisions. Tension. None of the above.
A spring.
There are only two forces exerted on the 1-meter long stick shown in the figure (imagine it is floating in space, for example). The stick is not uniform, with its center of mass 70 cm from the left end of the stick, as indicated by point A in the figure. When measured with respect to an axis through the center of mass (point A), the magnitude of the net torque resulting from the forces exerted on the stick is _______.
CORRECT ANSWER: 15.2 N*m
There are only two forces exerted on the 1-meter long stick shown in the figure (imagine it is floating in space, for example). The stick is not uniform, with its center of mass 70 cm from the left end of the stick, as indicated by point A in the figure. The net force exerted on the meter stick is _______.
CORRECT ANSWER: 76 N
There are only two forces exerted on the simple meter stick shown in the figure (imagine it is floating in space, for example). The stick is otherwise free to move. The net force exerted on the meter stick is _______.
CORRECT ANSWER: 76 N
What kind of stress is being applied to the cylinder in the figure?
CORRECT ANSWER: Compressive
What are the appropriate units for stress?
CORRECT ANSWER: Pa
What kind of stress is being applied to the cube in the figure?
CORRECT ANSWER: Shear
What kind of stress is being applied to the cylinder in the figure?
CORRECT ANSWER: Tensile
A person with mass M stands on a ladder of mass m that leans against a frictionless vertical wall and makes an angle of 53° measured from the horizontal. The ladder does not slip on the horizontal surface due to a static frictional force between the ladder and the ground. Some of the forces exerted on the ladder can produce torques on the ladder. Using the contact point between the ladder and the ground as a reference, which force(s) exerted on the ladder produce counterclockwise torques?
CORRECT ANSWER: The force of the wall on the ladder
A person with mass M stands on a ladder of mass m that leans against a frictionless vertical wall and makes an angle of 53° measured from the horizontal. The ladder does not slip on the horizontal surface due to a static frictional force between the ladder and the ground. For this ladder, which of the statements is true?
CORRECT ANSWER: The ladder is in static equilibrium.
What is required for a rigid body to be in static equilibrium?
CORRECT ANSWER: The rigid body must exhibit no translational motion and no rotational motion.
There are only two forces exerted on the rod shown in the figure (imagine it is floating in space, for example). The rod is not uniform, with its center of mass shifted to the right, as indicated by point A in the figure. For the forces shown, which of the statements is true?
CORRECT ANSWER: The rod is in neither rotational nor translational equilibrium.
There are only two forces exerted on the uniform rigid rod shown in the figure (imagine it is floating in space, for example). The rod is otherwise free to move. For the forces shown, which of the statements is true?
CORRECT ANSWER: The rod is in rotational equilibrium but not translational equilibrium.
There are only two forces exerted on the uniform rigid rod shown in the figure (imagine it is floating in space, for example). The rod is otherwise free to move. For the forces shown, which of the statements is true?
CORRECT ANSWER: The rod is in translational equilibrium but not rotational equilibrium.
What is required for a rigid body to be in translational equilibrium?
CORRECT ANSWER: The sum of the forces exerted on the rigid body must be zero.
What is required for a rigid body to be in rotational equilibrium?
CORRECT ANSWER: The sum of the torques due to all the forces exerted on the body must be zero.
A person with mass M stands on a ladder of mass m that leans against a frictionless vertical wall and makes an angle of 53° measured from the horizontal. The ladder does not slip on the horizontal surface due to a static frictional force between the ladder and the ground. Some of the forces exerted on the ladder can produce torques on the ladder. Using the contact point between the ladder and the ground as a reference, which force(s) exerted on the ladder produce clockwise torques?
CORRECT ANSWER: The weight of the ladder and the weight of the person
When a tensile or compressive stress is applied to a rigid body and the stress is small enough such that the object returns to its original shape when the stress is removed, then the ratio of stress/strain is equal to __________.
CORRECT ANSWER: Young's modulus
A tensile stress is applied to a cylinder of length L0 and cross-sectional area A as shown in the figure. How do you calculate the strain on the cylinder that results from this applied stress?
CORRECT ANSWER: delta L over L sub 0
When forces are exerted on an object, sometimes those forces will cause the object to be stretched, squeezed, or twisted. We define the deformation, which is the stretching, squeezing, or twisting of the object, as __________.
CORRECT ANSWER: strain
When forces are exerted on an object, sometimes those forces will cause the object to be stretched, squeezed, or twisted. We define the strength of the force that might cause an object to be stretched, squeezed, or twisted as __________.
CORRECT ANSWER: stress
When a volume stress is applied to a rigid body and the stress is small enough such that the object returns to its original shape when the stress is removed, then the ratio of stress/strain is equal to __________.
CORRECT ANSWER: the bulk modulus
When a shear stress is applied to a rigid body and the stress is small enough such that the object returns to its original shape when the stress is removed, then the ratio of stress/strain is equal to __________.
CORRECT ANSWER: the shear modulus
An object will be stable if Its center of gravity is below its highest point. Its center of gravity lies over its base of support. Its center of gravity lies outside its base of support. The height of its center of gravity is less than 1/2 its total height.
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. Equal to the weight you are lifting. Smaller than the weight you are lifting.
Larger than the weight you are lifting.
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? YA > YB YA = YB YA < YB Not enough information to tell
YA > YB
A very rigid material—one that stretches or compresses only slightly under large forces—has a large value of Tensile strength. Elastic limit. Density. Young's modulus.
Young's modulus.
An object is in equilibrium if = 0 Either A or B Both A and B
Both A and B
There are only two forces exerted on the simple meter stick shown in the figure (imagine it is floating in space, for example). The stick is otherwise free to move. The forces are exerted at theta is equal to 30 degrees measured from the meter stick. The net force exerted on the meter stick is __________.
CORRECT ANSWER: 0 N
There are only two forces exerted on the simple meter stick shown in the figure (imagine it is floating in space, for example). The rod is otherwise free to move. When measured with respect to an axis through the center of the meter stick, the net torque resulting from the forces exerted on the meter stick is _______.
CORRECT ANSWER: 0 N*m
There are only two forces exerted on the simple meter stick shown in the figure (imagine it is floating in space, for example). The stick is otherwise free to move. The forces are exerted at theta is equal to 30 degrees measured from the meter stick. When measured with respect to an axis through the center of the meter stick, the net torque resulting from the forces exerted on the meter stick is _______.
CORRECT ANSWER: 12.5 N*m
