A person pulls a 50. kg box pictured below with a force of 100. N.  The coefficient of kinetic friction is 0.15.  How much of the force acts in the direction of motion?How much energy is transferred (via working) by the person who pulls the box a distance of 10. m?
Is the box moving at constant speed? Explain how you know. What does this tell you about the kinetic energy Ek of the system?
How much energy is stored as internal energy due to friction in the pulling process over the 10.m?
What eventually happens to this energy?

Aseries circuit consists of a resistor with r = 20 ? , a capacitor with c = 0.01 f, and a decaying battery with e = 300e? 5t. if the initial charge is 0, find the charge as a function of time t

Calculate the mass of an object that has a momentum of 100kg x m/sec and velocity of 4 m/sec

The frequency of vibrations of a vibrating violin string is given by f = 1 2l t ρ where l is the length of the string, t is its tension, and ρ is its linear density.† (a) find the rate of change of the frequency with respect to the following. (i) the length (when t and ρ are constant) (ii) the tension (when l and ρ are constant) (iii) the linear density (when l and t are constant) (b) the pitch of a note (how high or low the note sounds) is determined by the frequency f. (the higher the frequency, the higher the pitch.) use the signs of the derivatives in part (a) to determine what happens to the pitch of a note for the following. (i) when the effective length of a string is decreased by placing a finger on the string so a shorter portion of the string vibrates df dl 0 and l is ⇒ f is ⇒ (ii) when the tension is increased by turning a tuning peg df dt 0 and t is ⇒ f is ⇒ (iii) when the linear density is increased by switching to another string df dρ 0 and ρ is ⇒ f is ⇒