On a hot day, you are in a sealed, insulated room. the room contains a refrigerator, operated by an electric motor. the motor does work at the rate of 378 w when it is running. the refrigerator removes heat from the food storage space at a rate of 450 w when the motor is running. in an effort to cool the room, you open the refrigerator door and let the motor run continuously. at what net rate is heat added to (+) or subtracted from (−) the room and all of its contents?

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

365.25 earth days are in the year of a light year