Things You Thought You Knew – Force, Heat, & Speed

What It Covers

Neil deGrasse Tyson explains the physics distinctions between force versus pressure, heat versus temperature, and speed versus acceleration, revealing how these commonly confused concepts manifest in everyday phenomena from knife sharpness to tornado destruction.

Key Questions Answered

• •Force versus Pressure: Pressure equals force divided by area. Snowshoes and polar bear paws spread weight over larger surface areas to prevent sinking through ice, while sharp knives concentrate force on tiny blade edges to cut effortlessly through food with minimal applied force.
• •Tornado Destruction Mechanism: Tornadoes explode houses outward because low pressure outside creates differential pressure across walls. Even one-tenth pound per square inch difference generates thousands of pounds of total force across an entire wall, exceeding structural capacity and turning homes into matchsticks.
• •Heat versus Temperature: Temperature measures average kinetic energy of vibrating molecules, while heat represents the total sum of all molecular energies. A coffee cup at 210 degrees Fahrenheit has higher temperature than the ocean, but the ocean contains vastly more total heat energy to power hurricanes.
• •Acceleration versus Speed: Bodies cannot detect constant speed, only changes in velocity. Earth rotates at 800 miles per hour and orbits the sun at 18 miles per second, yet humans feel nothing. Acceleration, deceleration, and directional changes trigger physical sensations, making sports cars thrilling despite lower top speeds.