Newton's Laws - Mission NL9 Detailed Help

A 900-kg rightward-moving car encounters 4500-N of resistive forces as it skids to a stop. Fill in all blanks in the diagram below and determine the magnitude of the acceleration (in m/s/s) of the car. (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 determine the acceleration of the object from knowledge of all the individual forces. The following method will assist your solution to the problem.
  • One of the three individual forces (Ffrict) is explicitly stated. The force of gravity can be determined from the object's mass (see Formula Fix section; use g = 10 N/kg). Since there is no vertical acceleration, the two vertical forces must balance; thus, the normal force is equal to the force of gravity.
  • The net force is the vector sum of all the forces. Since all three forces are known, they may be added as vectors to determine the net force (use the link in Hot Link section if necessary).
  • The acceleration of the object is found using Newton's second law equation: a = Fnet/m. Since both Fnet and m are known, plug and chug and you have your acceleration value.

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