Newton's Laws - Mission NL9 Detailed Help

A 2-kg pail is attached to a cable and raised upward with a constant speed of 1.5 m/s. Fill in all blanks in the diagram below and determine the tension force (in Newtons) in the cable. (Use the approximation that g ~ 10 N/kg.) ... 
(Note: Numbers are randomized numbers and likely different from the numbers listed here.)

The big idea in this problem is to use the idea of a constant velocity and a balance of forces to determine the value of an individual force - Ftens. The following method will assist your solution to the problem.
  • The acceleration of the object is not explicitly stated. The speed is stated, but not the acceleration. The fact that the speed and direction are constant is a clear indication that the acceleration must be 0 m/s/s.
  • The net force can now be determined using Newton's second law equation: Fnet = m • a. Clearly if the acceleration is 0 m/s/s, the individual forces balance and the net force must be 0 N - consistent with the equation.
  • The force of gravity can be determined from the object's mass (see Formula Fix section; use g = 10 N/kg).
  • Since there is a balance of forces, the tension force is equal to the force of gravity. That was easy!!

The mass of an object is mathematically related to its weight by the equation: 
Weight = Fgrav = mass • g

where g is the gravitational field strength. The value of g on Earth is 9.8 N/kg (approximately 10 N/kg).


The relationship between net force (Fnet), mass (m) and acceleration (a) is expressed by the equation:
a = Fnet / m