1. A child swings a toy of mass 0.05 kg on a string of length 1.9 m in a horizontal circle at constant speed so that the string is nearly horizontal. The toy has a period of 0.6 s. The amount of centripetal force in the string is most nearly (A) 2 N (B) 5 N (C) 10 N (D) 20 N

2. For the same toy in a circular path as the previous problem, the net centripetal force on the toy and its acceleration are
(A) both radially inward. (B) perpendicular to each other. (C) both zero. (D) both tangent to the circle.

The human body stores chemical energy from digested food. some of the chemical energy is converted into mechanical energy when the body moves. which statement best supported by this information

The ultracentrifuge is an important tool for separating and analyzing proteins. because of the enormous centripetal accelerations, the centrifuge must be carefully balanced, with each sample matched by a sample of identical mass on the opposite side. any difference in the masses of opposing samples creates a net force on the shaft of the rotor, potentially leading to a catastrophic failure of the apparatus. suppose a scientist makes a slight error in sample preparation and one sample has a mass 10 mg larger than the opposing sample. if the samples are 12 cm from the axis of the rotor and the ultracentrifuge spins at 70,000 rpm, what is the magnitude of the net force on the rotor due to the unbalanced samples? ( be thorough on your answer)

The law of reflection states that the angle of reflection is equal to the angle of