Question: A rightward force is applied to a crate to push it across the floor at a constant speed. Ignore air resistance.

Answer: Up- Normal Left- Friction Down- Gravity Right- Applied

Question: A rightward force is applied to a dresser to accelerate it to the right across the bedroom floor. Ignore air resistance.

Answer: Up- Normal Left-Friction Down- Gravity Right- Applied + Extended

Question: A rightward-moving car is skidding to a stop across a level roadway with locked wheels. Ignore air resistance.

Answer: Up- Normal Left- Friction Down- Gravity

Question: A football is moving upward and rightward towards the peak of its trajectory. Ignore air resistance.

Answer: Down- Gravity

Question: The cabin of a small freight elevator is secured to a motor by a cable and is moving upward with a constant speed. There is no contact between the cabin and the elevator shaft. Ignore air resistance.

Answer: Up- Tension Down- Gravity

Question: A downward-moving skydiver is falling with a constant speed.

Answer: Up- Air Resistance Down- Gravity

Question: A hockey puck glides to the right across the ice at a constant speed. Ignore air resistance.

Answer: Up-Normal, Down-Gravity

Question: A sledder has reached the bottom of a hill and is coasting to the right while slowing down along the loosely-packed snow. Ignore air resistance.

Answer: Up- Normal, Left-Friction, Down-Gravity

Question: A football, originally kicked at an 40-degree angle to the horizontal, is at the peak of its trajectory. Ignore air resistance.

Answer: Down- Gravity

Question: A downward-moving skydiver who has just opened the parachute is slowing down. (Diagram the forces on the skydiver/parachute combination.)

Answer: Up - Air Resistance + Extended Down- Gravity