Via LaughingSquid
To find out how individuals measure big forces accurately, Veritasium host Derek Muller visited the National Institute of Standards and Technology (NIST) to learn more about their machine that does just that. It houses a stack of 20 masses, equaling 50,000 pounds, to “create a maximum force of 1,000,000 pounds of force.” So far, they believe that their machine holds the largest mass objects ever calibrated in the world.
Before visiting NIST in Washington DC I had no idea machines like this existed. Surely there’s an accurate way to measure forces without creating such a huge known force?! Nope. This appears to be the best way, with a stack of 20 x 50,000 lb masses creating a maximum force of 4.45 MN or 1,000,000 pounds of force. I also wouldn’t have thought about all the corrections that need applying – for example buoyancy subtracts about 125 pounds from the weight of the stack. Plus the local gravitational field strength must be taken into account. And, the gravitational field varies below grade. All of this must be taken into account in order to limit uncertainty to just five parts per million (.0005%)