5.71 When a crate with mass 25.0 kg is placed on a ramp that is inclined at an angle a below the horizontal, it slides down the ramp with an acceleration of 4.9 m/s. The ramp is not frictionless. To increase the acceleration of the crate, a downward vertical force F is applied to the top of the crate. What must F be in order to increase the acceleration of the crate so that it is 9.8 m/s? How does the value of F that you calcu- late compare to the weight of the crate?