A uniform plank rests on supports at both ends, and a worker stands on it as shown. The plank is stationary and $g=9.8m/s^2$. What upward force does the left support exert?

A 6.0 m uniform beam of mass 15 kg is supported at both ends. A 30 kg box is 5.0 m from the left end. With $g=9.8m/s^2$, what is the upward force at the right support?

A 5.0 m uniform horizontal shelf of mass 12 kg is hinged at the left end and held by a vertical cable at the right end. A 20 kg sign hangs 4.0 m from the hinge. With $g=9.8m/s^2$, what is the cable tension?

A 3.0 m uniform beam of mass 10 kg is hinged at the left end. A vertical cable pulls up 2.0 m from the hinge, and a 15 kg lamp hangs at the right end. If $g=9.8m/s^2$, what is the cable tension?

A uniform board is supported at the two labeled points, and a crate rests on it as shown. If $g=9.8m/s^2$, what upward force acts at the left support?

A 5.0 m uniform beam of mass 10 kg is supported at both ends. A 12 kg device rests 4.0 m from the left end. With $g=9.8m/s^2$, what is the upward force at the right support?

An 8.0 m uniform beam of mass 25 kg is supported at both ends. A 45 kg person stands 2.0 m from the left end, and a 15 kg crate is 7.0 m from the left end. What is the left support force? Use $g=9.8m/s^2$.

A uniform beam is hinged at the left end. A vertical cable pulls up from the beam, and a sign hangs at the right end as shown. With $g=9.8m/s^2$, what is the cable tension?

A uniform beam is supported at both ends, with the loads positioned as shown. What is the right support force? Use $g=9.8m/s^2$.

A uniform bar is supported at the two labeled points, and a load hangs from it as shown. What upward force is at the left support? Use $g=9.8m/s^2$.

A negligible-mass seesaw has a pivot 2.0 m from a 30 kg child and 1.5 m from an unknown mass on the other side. It balances horizontally. What is the unknown mass? Use $g=9.8m/s^2$.

A 6.0 m uniform beam of mass 20 kg pivots 2.0 m from the left end. A 30 kg box is at the left end, and an unknown mass is at the right end. What mass balances the beam? Use $g=9.8m/s^2$.

A uniform beam pivots at the labeled point, with a known mass at the left end and an unknown mass at the right end as shown. What mass balances the beam? Use $g=9.8m/s^2$.

A negligible-mass seesaw balances with a 45 kg child 1.2 m left of the pivot and an unknown mass 1.8 m right of the pivot. What is the unknown mass? Use $g=9.8m/s^2$.

A negligible-mass bar balances about a pivot. A 12 kg mass hangs 1.0 m to the left, and an unknown mass hangs 0.75 m to the right. What is the unknown mass? Use $g=9.8m/s^2$.

A uniform beam is hinged at the left end. A vertical cable at the right end supports the beam, and an unknown crate hangs from the beam as shown. What is the crate's mass? Use $g=9.8m/s^2$.

A negligible-mass beam pivots at the labeled point. A downward force and an unknown hanging mass act on opposite sides of the pivot as shown. What mass balances the beam? Use $g=9.8m/s^2$.

The diagram shows a hinged uniform beam with a vertical cable at the right end and an unknown mass hanging from the beam. What is the mass? Use $g=9.8m/s^2$.

A rigid shop sign is motionless and not beginning to rotate. Which conditions must both be true?

A long rod has two equal opposite forces applied at different points, so the net force is zero but the torques do not cancel. What can happen?

Newton's first law in rotational form is best summarized by which statement?

Which set of equations represents static equilibrium for a horizontal beam in a plane?

A student wants the right support force on a beam without first finding the left support force. About which point should she sum torques?

A balanced seesaw has one child on each side. If the left child slides farther from the pivot and nothing else changes, what would restore rotational equilibrium?

A student sums torques about the center of a uniform beam with an off-center crate and two unknown support forces. What is the tradeoff of that pivot choice?