A man dressed in all black is walking down a country lane. Suddenly, a large black car with no lights on comes around the corner and screeches to a halt. How did the car's driver know he was there?

this is tricky

While sitting motionless in a 5 kg friction free wagon, an 80kg clown catches a 15 kg cannonball traveling horizontally at 20 m/s. After the cannonball is caught, at what speed do the clown, wagon, and ball move?

An illustration of a nuclear reactor. There are 3 parallel lines sticking half out of the reactor labeled rods containing uranium. There are parallel rods in the reactor labeled neutron-absorbing material. It is labeled nuclear reactor.

a motor pulls up a block suspended on a string, so that the tension in the string is equal to the qeight force on the block. the block has mass m, the distance raised is h and the power output of the motor is P.

Which of these is the best exclamation for why to negatively charged balloons, if put close, will repel? A. Charged objects sin little lightning bolts of electrons across the space between the two balloons B.

A balloon filled with 2.00 L of helium initially at 1.25 atm of pressure rises into the atmosphere. When the surrounding pressure reaches 410. mmHg, the balloon will burst. If 1 atm = 760.

The kinetic energy of a moving object is equal to the work required to bring it to its speed from rest, or the work the object can do while being brought to rest.

An engineer wants to set up simple password protection with no usernames for some switches in a lab, for the purpose of keeping curious co-workers from logging into the lab switches from their desktop PCs.

How are frequency and wave period related?

Which statement best defines inertia?

When you put a ice cube in a warm drink and the ice cube thermal energy decreases and the drink thermal energy increases, how does the energy move? What is the situation when the ice cube would give off the heat?