Q&A for How to Calculate Weight from Mass

Return to Full Article

Search
Add New Question
  • Question
    How do I get the gravitational force and multiply it by the mass?
    Community Answer
    Gravitational force is proportional the two bodies' masses and the gravitational constant and is inversely proportional to the square of the distance between them. F= (m1 (Earth)*m2 (observed body)*G(constant))/r/r. G= 6.67408 × 10-11 m3 kg-1 s-2. However, for the sake of weight we usually take the gravitational accelration (g) which is equal to 9.81 m/s/s, usually rounded to 10 m/s/s. G (gravitational force/weight) = g (gravitational accelration) * m (mass of the observed body). If you use both methods, the two Gs should be equal barring some rounding errors.
  • Question
    Does a scale measure weight or mass?
    Community Answer
    It measures weight, because it measures the force gravity exerts on an object. But since we know what the gravitational constant is on Earth, we can convert that weight into mass (and many scales simply show the mass because they're calibrated to do so).
  • Question
    If the mass of an object is 25kg on earth, what will be its weight on the moon?
    Community Answer
    The gravitational field strength of the moon is 1.6N/kg. This means that the weight of a 1kg mass object on the moon is 1.6N. Weight = mass x gravitational field strength Therefore, 25 kg multiplied by 1.6 N/kg, is 40 N.
  • Question
    What if weight is expressed in kg? How do you convert it into mass in Newtons?
    Community Answer
    The units of weight are in Newtons. If its in kilograms, its the mass of the object, not the weight.
  • Question
    What is the mass of an object that has a weight of 80N on the moon?
    Community Answer
    We already have the weight and the gravity on the moon is 1.6m/s square so we will divide the F (weight) by g. Divide 80 N by 1.6 m/s square, and you will get the mass.
  • Question
    Is my weighing machine showing mass or weight?
    Community Answer
    Weighing machines show the weight of the object. Mass refers to what it is composed of.
  • Question
    What does 3 kg/m^3 mean?
    Community Answer
    This means kilograms per cubic meter.
  • Question
    How do I calculate weight from mass if I know the gravity?
    Community Answer
    Multiply the mass (in kg) by the acceleration due to gravity (in m/s/s). Your answer is in Newtons (N). For example, a 100-kg object on earth (acceleration due to gravity: 9.81 m/s/s) weighs 100 x 9.81 = 981 N.
  • Question
    The mass of an object is 6 kg on the surface of Earth. What will its mass be on the surface of the moon?
    Community Answer
    6 kg. The mass remains the same, only the weight changes because there is a change in the gravitational acceleration.
  • Question
    The mass of a stone is 100g. What is the weight of the stone?
    Community Answer
    The weight is (0.1 kg)(9.80665 m/s²) = 0.980665 Newton.
  • Question
    What if the mass is in g, not kg?
    Community Answer
    Divide the mass by 1000. That will convert it to kg. Then use the formula above as usual.
  • Question
    What is 200g converted to weight?
    Community Answer
    The weight is F = (mass)(force of gravity) = (0.2 kg)(9.8 m/s²) = 1.96 kg m/s² = 1.96 Newtons.
  • Question
    If a bathroom scale says something 'weighs' 100 lbs, is that actually its mass and it really weighs 32,200 pounds?
    Community Answer
    No. A scale measures weight, not mass. Remember, mass is a measure of the amount of matter in an object, while weight measures the force of gravity on that object. If a scale says "100 pounds," that is the object's "weight" (at the surface of the Earth).
  • Question
    How do you find mass with just force
    Johnthan Fuentes
    Community Answer
    This is not possible. The equation you'd use is F=ma, where F = the force (in N), m = mass (kg), and a = acceleration (in m/s^2). To calculate mass of an object from a known force, you'll need to know the acceleration of that object.
  • Question
    How do I calculate mass from weight?
    Community Answer
    Multiply both together to get the force. Remember the formula: F= m×w, F= Force, m=mass, w=weight. So, just multiply it. For example, 60kg × 1.67 = 100.2N.
  • Question
    An equipment weighs 529N and 209N on Earth and Mars respectively. What is the acceleration due to the gravity of Mars?
    Cabbache
    Community Answer
    The mass of the equipment can be found by F = ma, 529N = m x 9.81m/s^2, so m = 53.92Kg. Use F = ma again to find the acceleration on Mars. 209/53.92 = 3.875m/s^2.
  • Question
    How do I find the average weight of a number of people?
    Cabbache
    Community Answer
    You add up their weight, and divide by the number of people. It's just finding the mean average.
  • Question
    You serve a volleyball with a mass of 2.1 kg. The ball leaves your hand with a speed of 30m/s. Calculate the ball's energy.
    Cabbache
    Community Answer
    K.E = 1/2 x mv^2 = 1/2 x 2.1 x 30 x 30 = 945 Joules.
Ask a Question

      Return to Full Article