A mechanical device requires 420 J of work to do 230 J of work to lift a crate. What is the efficiency of the device? 190% 0.5% 183% 55%

Two radioactive nuclei A and B are present in equal numbers to begin with. Three days later, there are 4.04 times as many A nuclei as there are B nuclei. The half-life of species B is 1.37 days. Find the half-life of species A (in days).

What is the pH of a solution with [H+] = 2.3 10-12? A-2.3 B-12 C-11.64 D-1.64

When did most of the cratering on the moon occur?

you add 8950 J of heat to 174 g of iron. What is the temperature of the iron (c=452 J / (kj * C degrees)) ?

Explain using your own why you, always give a unit when reporting measurement

Which has more gravitational potential energy - - a cliff diver at the top of the cliff or a cliff diver at the bottom of the cliff?

A skydiver with a mass of 60 kg jumps from an airplane. Five seconds after jumping the force of air resistance is 300 N. What is the acceleration of the sky diver, five seconds after jumping?

How many basic wave forms are there? A.) 1 B.) 2 C.) 3 D.) 4

How much power is reqired to lift a 10-n box 2 meters

Dolphins and other sea creatures can leap to great heights by swimming straight up and exiting the water at a high speed. A 200 kg dolphin leaps straight up to a height of 7.8 m.