Which scientists discovered the two radioactive elements radium and polonium

A crate is being pulled to the right a distance of 10 m, with applied force 120 N at an angle of 60 degrees to the ground, if the friction on the box is 10 N, calculate the net work done on the crate?

An apple drops from a tree and hits the ground in 1.5s what is its speed just before it hits the ground?

Why did Heisenberg come up with the uncertainty principle? Your answer

A 1.0 kg pendulum has an initial total energy of 10 J. Calculate the energy lost as heat if the pendulum is 0.10 m high and is traveling at 4.0 m/s.

The sun is directly overhead at the equator on what day of the year?

A geologist estimates that a large boulder weighs 7840 N. What should he estimate the mass of this boulder to be? A. 650 kg B. 740 kg C. 780 kg D. 800 kg

Two objects have the same momentum. Do the velocities of these objects necessarily have (a) the same directions and (b) the same magnitudes? Give your reasoning in each case.

If you keep voltage constant and increase resistance resistance, what happens to current?

A scene in a movie has a stuntman falling through a floor onto a bed in the room below. The plan is to have the actor fall on his back, but a researcher has been hired to investigate the safety of this stunt.

During energy transformation, all energy systems: are a. 100 percent efficient b. lose energy c. gain heat energy d. create energy