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# Physics Force 1

### Physics Force Stuff

Question | Answer |
---|---|

Accelerations are produced by ____________ | Forces |

How does acceleration of an object change in relation to its mass? | Inversely proportional |

What is the acceleration of an object when it reaches terminal velocity? | 0 m/s2 |

A heavy person and a light person parachute together and wear the same size parachutes. Assuming they open their parachutes at the same time, which person reaches the ground first? | The heavy person. |

A 10-kg brick and a 1-kg book are dropped in a vacuum. What is the force of gravity on the 10-kg brick? | The same as the force on the 1-kg book. |

Will a 10-kg object on earth weigh more or less on the moon? | less |

Suppose the force of friction on a sliding object is 10N. What are the forces needed to maintain a constant velocity? | 10N |

An apple weighs 1N. What is the net force on the apple when held above your head? | 0N |

An apple weights 1N. What is the net force on the apple when it is in free fall? | 1N |

A girl pulls on a 10-kg wagon with a constant force of 30N. What is the wagons acceleration? | 3.0 m/s2 |

An object has a constant mass. A constant force on the object produces constant __________. | Acceleration |

A push on a 1kg brick accelerates the brick. Neglecting friction, to equally accelerate the brick, one would have to push with how much more force? | 10 times as much force. |

A rock is thrown vertically into the air. What is the net force on it at the very top of its trajectory? More than it's weight? Less than it's weight? Equal to it's weight? | It's weight. |

A block is dragged without acceleration in a straight line path across a level surface by a force of 6N. What is the friction force between the block and the surface? | 6N |

Suppose a particle is accelerated through space by a constant 10-N force. Suddenly the particle encounters a second force of 10-N in a direction opposite to that of the first force. What happens to the particle? | Continues at the speed it was at when it encountered the second force. |

A tennis ball and a solid steel ball the same size are dropped at the same time. In the absence of air resistance, which ball has the greater acceleration? | They both have the same acceleration. |

The terminal speed for a person parachuting (with the chute open) is about ____________? | 15 km/h |

Aunt Minnie throws a rock downward, and air resistance is negligible. What is the acceleration of the rock compared to being dropped? (more, less, or the same?) | More |

As Bob falls from a high flying stationary helicopter, his velocity increases and his acceleration ____________? | Decreases |

When the angle of an incline with a block resting on it increases, the normal support force does what? | Decreases |

As a ball rolls from the rim of a bowl downward toward the bottom, its rate of gaining speed __________ (remains the same, increases, decreases?) | Decreases |

A speeding truck slams its brakes and it skids to a stop. If the trucks total mass were doubled, its skidding distance would be what? | twice as far. |

If the force acting on a cart doubles, what happens to the cart's acceleration? | It doubles |

Suppose a cart is being moved by a force. If suddenly, a load is dumped into the cart, causing the carts mass to double, what happens to the carts acceleration? | It halves. |

A girl whose weight is 200N hangs from a bar supported by two vertical strands of rope. What is the tension in each strand? | 100N |

A 10-N falling object encounters 4-N of air resistance. What is the magnitude of the net force on the object? | 6N |

A car has a mass of 1000 kg and accelerates at 2 meters per second. What is the magnitude of the forces acting on the car? | 2000N |

A tow truck exerts a force of 3000N on a car, accelerating it at 2 m/s2. What is the mass of the car? | 1500kg |

A 747 jumbo jet has a mass of 30,000kg. The thrust for each of four engines is 15,000N. What is the jet's acceleration when taking off? | 2 m/s2 |

You pull horizontally on a 50kg crate with a force of 500N, and the friction force on the crate is 250N. What is the acceleration of the crate? | 5 m/s2 |

How much force is needed to accelerate a 2kg physics book to an acceleration of 6 m/s2? | 12N |

A jumbo jet cruises at a constant velocity when the total thrust of the engines on the jet is 40,000N. How much air resistance acts on the jet? | 40,000 N. |

A 10-N falling object encounters 10-N of air resistance. What is the magnitude of the net force on the object? | 0N |

ToF: The combination of all the forces that act on an object is called the net force. | True |

ToF: The acceleration of an object is inversely proportional to the net force acting on it. | False |

ToF: The force that supports the weight of a book lying at rest on a tabletop is called a normal force. | True |

ToF: A fluid can be either a liquid of a gas. | True |

ToF: The pascal is a unit of force. | False |

ToF: The speed of an object dropped in air will continue to increase without limit. | False |

ToF: An object in free fall has zero acceleration. | False |