Measuring Forces
Science: KS3, topic 1.6.10
Measuring Forces
You can use moments to measure the force that a muscle is exerting to lift an object.
Forces exerted by muscles
- Imagine standing up with your upper arm vertical and your lower arm horizontal out in front of you.
- If you were holding a 1 kg mass in your hand, there would be a force of 10 N being exerted downwards by the mass on your hand.
Moments
- Using moments, you can work out the size of the force your bicep is exerting on your forearm to keep your arm still.
- Anticlockwise moment = clockwise moment.
- 10 × mass × distance from elbow to mass = force × distance from elbow to bicep
- Rearranging will then give you the equation;
- Force of bicep = \frac{(10 \;N × distance \;from\; elbow\; to\; mass)}{distance \;from \;elbow \;to\; bicep}
Test yourself on Measuring Forces
What is the closest approximate to the value of gravitational field strength on Earth?
What do we use to measure the force that a muscle is exerting to lift an object?
Two people hold the same mass with their arms in the same position. Person A's bicep attaches closer to the elbow than Person B's bicep. Whose bicep must exert the greater force to hold the mass still?