For the decomposition of urea in the reaction: CO(NH2)2(aq) + 2 H2O(l) → 2NH4 + (aq) + CO3 2− (aq) the pseudo first-order rate constant is 1.2 × 10−7 s −1 at 60°C and 4.6 × 10 −7 s −1 at 70°C. A) Estimate the activation energy b) Calculate the entropy of activation of the reaction and comment on the value.

Awoman stands a distance d from a loud motor that emits sound uniformly in all directions. the sound intensity at her position is an uncomfortable 2.0×10-3 w/m2. at a distance 2.6 times as far from the motor, what are (a) the sound intensity and (b) the sound intensity level relative to the threshold of hearing?

The man of mass m1 and the woman of mass m2 are standing on opposite ends of the platform of mass m0 which moves with negligible friction and is initially at rest with s = 0. the man and woman begin to approach each other. derive an expression for the displacement s of the platform when the two meet in terms of the displacement x1 of the man relative to the platform.

If a hiker that weighs 600 newtons climbs a 50 meter hill, how much gravitational potential energy has the hiker gained?