Static Equilibrium

There must be equal amounts of mass on both sides of the center of mass (or center of gravity) of a system.

• True
• False

If an object remains at rest, then the sum of both the external torques and the external forces on the object must be zero.

• True
• False

An object can experience a net force without experiencing a net torque.

• True

• False

An object can experience a net torque without experiencing a net force.

• True

• False

An object is sitting stationary on a ramp. The force of friction is balanced by...

• The normal force

• The weight of the object

• The force of gravity acting down the ramp

• There is no friction force because the object is not moving.

Tags

NGSS.HS-PS2-1

An irregularly shaped object that is 10 m long is placed with each end on a scale. The scale on the right reads 96 N while the scale on the left reads 71 N. Where is the center of mass of this object located, relative to the geometric center (the middle) of the object?

• To the left

• To the right

• Directly in the middle

• Cannot be determined without more information

A mobile is shown in the figure. The horizontal supports have negligible mass. Assume that all the numbers given in the figure are accurate to two significant figures. What mass M is required to balance the mobile?

• 36 g
• 90 g
• 18 g
• 60 g

Tags

NGSS.HS-PS2-1

A uniform rod weighs 40 N and is 1.0 m long. It is hinged to a wall at the left end, and held in a horizontal position at the right end by a vertical string of negligible weight, as shown in the figure. What is the magnitude of the torque due to the string about a horizontal axis that passes through the hinge and is perpendicular to the rod? The hinge is very small with negligible friction.

• 5.0 N ∙ m
• 20 N ∙ m
• 10 N ∙ m
• 40 N ∙ m

To determine the location of the center of mass (or center of gravity) of a car, the car is driven over a scale on a horizontal floor. When the front wheels are over the scale, the weight recorded by the scale is 5800 N, and when the rear wheels are over the scale, the scale reads 6500 N. The distance between the front and rear wheels is measured to be 3.20 m. How far behind the front wheels is the center of mass located?

• 1.69 m
• 0.845 m
• 1.72 m
• 1.50 m

A uniform 40-N board supports two children weighing 500 N and 350 N.  If the support is at the center of the board and the 500-N child is 1.5 m from its center, how far is the 350-N child from the center?

• 1.5 m
• 2.7 m
• 2.1 m
• 1.1 m