A 0.4 kg ball moves in a horizontal circle of radius 0.5 m with speed 5 m/s. The centripetal force is:

A wheel of radius 0.3 m rotates at 100 rpm. The speed of a point on the rim is:

A 1 kg stone is whirled in a vertical circle of radius 0.5 m with speed 5 m/s at the bottom. The tension at the bottom is (g = 10 m/s^2):

A curve of radius 200 m is banked at 15 degrees. Without friction, the speed a car should travel is (g = 10 m/s^2, tan(15) = 0.268): <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 350 160" style="max-width:350px;margin:0.5em auto;display:block;"> <title>Banked curve — find the safe speed</title> <rect width="350" height="160" fill="#faf9f5" rx="8"/> <defs><marker id="ah-q06s3q4" markerWidth="8" markerHeight="6" refX="8" refY="3" orient="auto"><polygon points="0 0, 8 3, 0 6" fill="#c6613f"/></marker></defs> <line x1="50" y1="120" x2="230" y2="72" stroke="#14140f" stroke-width="2"/> <rect x="115" y="76" width="32" height="20" fill="#faf9f5" stroke="#14140f" stroke-width="1.5" transform="rotate(-15, 131, 86)"/> <line x1="131" y1="83" x2="119" y2="30" stroke="#c6613f" stroke-width="2" marker-end="url(#ah-q06s3q4)"/> <text x="106" y="28" font-family="sans-serif" font-size="10" fill="#c6613f">N</text> <line x1="131" y1="88" x2="131" y2="130" stroke="#14140f" stroke-width="1.5" marker-end="url(#ah-q06s3q4)"/> <text x="136" y="128" font-family="sans-serif" font-size="10" fill="#14140f">mg</text> <path d="M 90,120 A 40,40 0 0,1 100,112" fill="none" stroke="#14140f" stroke-width="1"/> <text x="94" y="134" font-family="sans-serif" font-size="10" fill="#14140f">15°</text> <line x1="50" y1="120" x2="95" y2="120" stroke="#14140f" stroke-width="1" stroke-dasharray="3,3"/> <text x="248" y="78" font-family="sans-serif" font-size="10" fill="#14140f">r = 200 m</text> <text x="248" y="92" font-family="sans-serif" font-size="10" fill="#14140f">v = ?</text> <text x="175" y="152" text-anchor="middle" font-family="sans-serif" font-size="10" fill="#14140f">v = √(rg tanθ)</text> </svg>

A car moving at 30 m/s can safely turn on a flat road with mu = 0.9. The minimum radius of the turn is (g = 10 m/s^2):