True or False Use a mini whiteboard Vector Quiz True or False Use a mini whiteboard

Which of the following statements about vectors and scalars are TRUE? A vector is a large quantity and a scalar is a small quantity. A scalar quantity has a magnitude and a vector quantity does not. A vector quantity is described with a direction and a scalar is not. Scalar quantities are path dependent quantities and vector quantities are not. A scalar quantity depends only upon the initial and final values of the quantity; this is not the case for vector quantities. The quantity 20 m/s, north is a speed and as such is a scalar quantity. The quantity 9.8 m/s/s is an acceleration value and as such is a vector quantity.

FALSE - This would never be the case FALSE - This would never be the case. Vectors simply are direction-conscious, path-independent quantities which depend solely upon the initial and final state of an object. Vectors are always expressed fully by use of a magnitude and a direction. FALSE - Both scalar and vector quantities have a magnitude or value expressed with a given unit; additionally, a vector quantity requires a direction in order to fully express the quantity. TRUE - Vectors are fully described by magnitude AND direction; scalars are not described with a direction. TRUE - Scalars such as distance would depend upon the path taken from initial to final location. If you run around the track one complete time, your distance will be different than if you take a step forward and a step backwards. The path MATTERS; distance (like all scalars) depends upon it. On the other hand, the displacement (a vector quantity) is the same for both paths. FALSE - Vectors are the types of quantities which depend only upon initial and final state of the object. For instance, the vector quantity displacement depends only upon the starting and final location. FALSE - This is certainly not a speed quantity; though the unit is appropriate for speed, the statement of the direction is inconsistent with speed as a scalar quantity. FALSE (a rather picky FALSE) - If a direction was included, then this would be an acceleration value. The unit is characteristic of acceleration but the lack of direction is inconsistent with acceleration being a vector quantity.

Free Fall Quiz True or False

An object that is free-falling is acted upon by the force of gravity alone. A falling skydiver which has reached terminal velocity is considered to be in a state of free fall. A ball is thrown upwards and is rising towards its peak. As it rises upwards, it is NOT considered to be in a state of free fall. An object in free fall experiences an acceleration which is independent of the mass of the object. A ball is thrown upwards, rises to its peak and eventually falls back to the original height. As the ball rises, its acceleration is upwards; as it falls, its acceleration is downwards. A ball is thrown upwards, rises to its peak and eventually falls back to the original height. The speed at which it is launched equals the speed at which it lands. (Assume negligible air resistance.) A very massive object will free fall at the same rate of acceleration as a less massive object. The value of g on Earth is approximately 9.8 m/s2. The symbol g stands for the force of gravity.

TRUE - Yes! This is the definition of free fall. FALSE - Skydivers which are falling at terminal velocity are acted upon by large amounts of air resistance. They are experiencing more forces than the force of gravity. As such, they are NOT free-falling. FALSE - Any object - whether rising, falling or moving horizontally and vertically simultaneously - can be in a state of free fall if the only force acting upon it is the force of gravity. Such objects are known as projectiles and often begin their motion while rising upwards. TRUE - The unique feature of free-falling objects is that the mass of the object does not effect the trajectory characteristics. The acceleration, velocity, displacement, etc. is independent of the mass of the object. FALSE - The acceleration of all free-falling objects is directed downwards. A rising object slows down due to the downward gravity force. An upward-moving object which is slowing down is said to have a downwards acceleration. TRUE - If the object is truly in free-fall, then the speed of the object will be the same at all heights - whether its on the upward portion of its trajectory or the downwards portion of its trajectory. TRUE - The acceleration of free-falling objects (referred to as the acceleration of gravity) is independent of mass. On Earth, the value is 9.8 m/s/s (the direction is down). All objects - very massive and less massive - experience this acceleration value. TRUE - Yes! Know this one! FALSE - Nope. A careful physics teacher will never call g the force of gravity. g is known as the acceleration of gravity. It might be best to call it the acceleration caused by gravity. When it comes to the force of gravity, we have yet another symbol for that - Fgrav. But that's a topic to be discussed in a later unit.