Question

If I am lifting a box with a force of 100 N and the box has an acceleration of 10 N, what is the mass of the box?

Answer 1

Answer:

a. How much force is required to lift a box of weight 100 N upwards with a constant acceleration of 6.0 m/s2?

b. How much upwards force is required to lower the same box with a downward acceleration of 3.0 m/s2?

a. As the box weighs 100 N, its mass is 100 N / 9.8 ms-2  =  10.2 kg.  To have an upward acceleration of 6.0 m/s2, there must be a net upward force of F =ma  =  10.2 kg x 6.0 m/s2 =  61.2 N.  The total upward force must be equal have a magnitude to overcome the downward force of gravity and to provide for the upward acceleration  Ftotal up = 100 N + 61.2 N  =  161.2 N.

b. There must be a net downward force F = ma = 10.2 kg x 3.0 m/s2  =  30.6 N upward.  There must be an upward force to counteract the downward force of gravity so that the resultant will be 30.6 N.  The equation necessary for this is 100 N - upward force =  30.6 N.  Solving for the upward force gives  69.4 N.

Explanation: