If the net force on an object is zero, what is its acceleration in an inertial frame?

A \(20\,\mathrm{N}\) weight hangs motionless from a vertical string. Find the string tension.

A car moves at constant velocity while air resistance is \(700\,\mathrm{N}\) backward. Find the forward driving force.

A \(5.0\,\mathrm{kg}\) block rests on a horizontal table. Find the normal force using \(g=9.8\,\mathrm{m\,s^{-2}}\).

An \(8.0\,\mathrm{kg}\) speaker hangs at rest from a vertical cable. Find the cable tension.

A box at rest is pulled right by \(9\,\mathrm{N}\). Find the leftward force needed for horizontal equilibrium.

A \(10\,\mathrm{kg}\) block rests on a frictionless \(20^\circ\) incline, held by a string parallel to the slope. Find the string tension.

A \(12\,\mathrm{kg}\) sign hangs from two identical cables, each \(30^\circ\) from the vertical. Find the tension in each cable and the horizontal force each cable exerts on the sign.

A \(12\,\mathrm{kg}\) crate is pulled by \(40\,\mathrm{N}\) at \(30^\circ\) above horizontal and remains at rest on a rough floor. Find the friction force and normal force, then the minimum \(\mu_s\) required for equilibrium.

A \(20\,\mathrm{kg}\) sign is held at a joint by a horizontal cable pulling left and a second cable pulling \(40^\circ\) above the horizontal to the right. A steady horizontal wind also pushes the sign right with \(90\,\mathrm{N}\). Find both cable tensions.