A force is a "push" or "pull" exerted on an object to move it or accelerate it. Newton's second law of motion describes how force is related to mass and acceleration, and this relationship is used to calculate force. In general, the greater the mass of an object, the greater the force required to move it.
Step
Part 1 of 2: Knowing the Formula
Step 1. Multiply the mass by the acceleration
The force (F) required to move an object of mass (m) with acceleration (a) is defined by F = m x a. So, force = mass multiplied by acceleration.
Step 2. Convert the numbers into SI values
The International System of Units (SI) for mass is the kilogram, and the SI unit for acceleration is m/s2 (meters per second squared). So, if mass and acceleration are expressed in SI units, then the SI unit of force is N (Newton).
For example, if the object's mass is 3 pounds, convert pounds to kilograms. 3 pounds = 1.36 kg, so the mass of the object is 1.36 kg
Step 3. To remember that weight and mass are two different things in Physics
If the weight of an object is expressed in N (Newtons), divide it by 9.8 to get the equivalent mass. For example, a weight of 10 N is equivalent to 10/9.8 = 1.02 kg.
Part 2 of 2: Using Formulas
Step 1. Find the force required to accelerate a 1000 kg car with an acceleration of 5 m/s2.
- Make sure all values are in correct SI units.
- Multiply the acceleration value (1000 kg) by 5 m/s2 to calculate the value.
Step 2. Calculate the force required to accelerate an 8-pound cart moving at 7 m/s2.
- First, convert all your units to SI. One pound equals 0.453 kg, so multiply that value by 8 pounds to determine mass.
- Multiply the new value for mass (3.62 kg) by the acceleration value (7 m/s2).
Step 3. Find the magnitude of the force acting on a basket weighing 100 N and an acceleration of 2.5 m/s2.
- Remember, 10 N equals 9.8 kg. So convert Newtons to kg by dividing the value by 9.8 kg. The new kg value for mass is 10.2 kg.
- Multiply the new mass value (10.2 kg) by the acceleration (2.5 m/s2).
Tips
- Always read the question carefully to determine whether the weight or mass is known.
- The definition of the Newton, the standard unit of force, is N = kg * m/s^2.
- Make sure all numbers have been converted to kilograms and m/s^2.
