On a sunny day with no wind, a balloon is filled with helium and floats away into the sky. eventually, the balloon pops. three cases of an identical balloon. in case a, the net pressure above the balloon points down, and the net pressure below the balloon points upward with a larger magnitude. in case b, the net lateral pressure is represented by several horizontal arrows on each side of the balloon pointing toward the balloon. in case c, the external pressure is represented by several arrows surrounding the balloon pointing inward and perpedicular to the balloon's surface. the internal pressure is represented by several arrows of greater magnitude inside the balloon that point radially outward. which case explains why the balloon pops at high elevation?

case a: the net pressure acting upward and downward on the balloon squeezes it until it bursts.

case b: the net lateral pressure squeezes the balloon until it bursts.

case c: the pressure inside the balloon is greater than the pressure outside the balloon, causing the balloon to expand until it bursts.

If the force on an object is in the negative direction, the work it does on the object must be [2 points a) negative. b) positive c) the work could be either positive or negative, depending on the direction the object moves

Since the investigative question has two variables, you need to focus on each one separately. thinking only about the first part of the question, mass, what might be a hypothesis that would illustrate the relationship between mass and kinetic energy? use the format of "if…then…because…” when writing your hypothesis.

Aroll in a paper machine is powered by a separately excited dc machine. operating point 1 (under load): the roll typically operates at 764 rpm and must provide 301 nm of torque to oppose the load of the paper. the armature voltage is 230v for this operating point operating point 2 (no load): when the load is removed the speed of the roll increases to 900 rpm (the field characteristics are unchanged) la ea dev m (a) calculate the maximum torque (units of nm) that the motor can supply with this applied voltage (b) calculate the value of the armature resistance, ra (in ohms) (c) at operating point 1 (loaded condition), the field current, i, and the total input power (armature field), are measured to be to be 10 a and 28,600 w respectively. use this information to calculate the value of the field resistance, rf (in ohms). (d) (d) at operating point 1 (loaded condition), calculate the motor efficiency. express your answer as a percent to at least 2 significant digits. (d) if the field voltage is reduced by 1/2, calculate the new stall torque (in nm) of the motor (f). if the field voltage is reduced by 1/2, calculate the new no-load speed (in rad/sec)