In one amusement park ride, riders enter a large verticalbarrel and stand against the wall on its horizontal floor. The barrel is spun up and the floor drops away. Ridersfeel as if they are pinned to the wall by a force somethinglike the gravitational force. This is a fictitious forcesensed and used by the riders to explain events in therotating frame of reference of the barrel. Explain in aninertial frame of reference (Earth is nearly one) whatpins the riders to the wall, and identify all of the realforces acting on them.

the answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this

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.

it is b. absorbs thermal energy