Physical Sciences, Part 6

Question 1: Define free fall, terminal velocity, fluid pressure, and torque.

Answer 1: Free fall: Free fall is a type of motion in which just gravity and no other forces are acting upon a mass. Terminal velocity: As it relates to fluids, terminal velocity is when an object ceases to accelerate and falls at a constant speed. This occurs when the resistant force of the air or fluid through which an object is moving is equal to the downward force, usually gravity. Fluid pressure: This refers to the concept that states that the force of pressure is dependent upon the depth and density of the fluid and the acceleration of gravity. The formula is P = pgh, where “P” is static fluid pressure, “p” is fluid density (mass divided by volume), “g” is the acceleration of gravity, and “h” is the depth of fluid.Torque: Torque is an influence that tends to change the rotational motion of an object. An equation to calculate torque is torque = force * lever arm. The lever arm is the perpendicular distance from the axis of rotation to the force.

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Question 2: Explain how mass affects the acceleration of a falling object.

Answer 2: The weight of an object is the force of gravity on the object, and may be defined as the mass times the acceleration of gravity: w = mg. Mass is the amount of matter an object contains. For instance, the mass of an object may be the same on the Moon and Earth, but the weight will be different. When an object falls, it will accelerate at the same speed regardless of its mass provided that gravity is the only force working on the object. Mass does not affect the acceleration of a falling object. An object’s shape may result in it being slowed down due to wind resistance, but this has nothing to do with its mass.

Question 3: Discuss the acceleration of an object that is thrown upward and discuss work done upon a stationary object.

Answer 3: When an object is thrown upward the acceleration at the top of its path is 9.8 meters per second squared (m/s2). This is Earth’s gravity (g) close to its surface. It is considered to be the acceleration of all objects when there is no resistance, such as that of air. When the object is at the top of its trajectory, it is not moving, so there is no air resistance.Work on a stationary object: If an object of a certain weight is held at a certain height for a certain amount of time, there is no work performed. This is because the formula for work performed is work is equal to force times distance, or displacement (W = F * d[cosT]). Displacement is a vector measurement, and there must be displacement for work to be done. If an object is being held up, forces are at work, but are canceling each other out. No work is being done.

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