In motion on an inclined experiment, a student measures the angle of inclined plane with a protractor whose uncertainty is Δθ=1 The acceleration of the motion due to gravity g along the inclined plane, which is has uncertainty due to the uncertainty of measuring the angle. Which one of the following is true about the uncertainty of acceleration Δa? a. Δa= gSinθ x Δθ
b. Δa= gCosθ x Δθ
c. Δa= gTanθ x Δθ
d. Δa= gSinθ

When a charged balloon sticks to a wall, the downward gravitational force is balanced by an upward static friction force. the normal force is provided by the electrical attraction between the charged balloon and the equal but oppositely charged polarization induced in the wall's molecules. if the mass of a balloon is 1.2 g, its coefficient of static friction with the wall is 0.71, and the average distance between the opposite charges is 0.80 mm, what minimum amount of charge must be placed on the balloon in order for it to stick to the wall? express your answer to two significant figures and include appropriate units.