W3.12 DYNAMICS EFF Word problems For each question sketch a picture and draw a FBD. 1) A 10-kg "dead donkey in cement" is pulled to the right across a rough floor (1#0) by a horizontal force of 40 N. If the "donkey" accelerates to the right at 1 m/s, what is the u between the floor and the "donkey"? 2) A horizontal force pushes a 20-kg crate to the right across a rough floor where u = 0.5. If the crate accelerates to the right at 6 m/s , what is the magnitude of the horizontal push? 3) A 40-kg safe is pulled to the right across a rough floor (1#0) by a rope angled at 36.870 above the horizontal. If the tension in the rope is 200 N and the safe accelerates to the right at 2.5 m/s, what is the u between the safe and the floor? 4) A large 1kg basketball falls 20 meters in 4 seconds starting from rest. (Hint: What is the acceleration?) What is the average drag force (air resistance) acting upwards on the ball as it falls? 5) A 4-kg book is pressed horizontally against a rough wall (170) by a force. If the book accelerates downward at 2 m/s and the coefficient of friction between the wall and the book is 0.4, what is the size of the force? 6) Drew, Bill and Keith push horizontally on Chuck (100-kg). Drew and Bill each push to the right with a force of "2F" and Keith pushes to the left with a force of "F". Chuck moves and accelerates to the right at 2 m/s across the rough floor where u = 0.5. What is the magnitude of Keith's push? 7) A block of unknown mass is pulled across a horizontal surface with a force of 50 N. If the u between the surfaces is 0.2 and the acceleration of the block is 5 m/s , what is the mass of the block? 8) A 10-kg child is pushed up a 36.870 ramp by a force, P (parallel to the surface of the ramp). If the child accelerates at 4 m/s (up the ramp) and the u between the surfaces is 0.2, what is the magnitude of P