What type of system allows matter and energy to enter and exit

Two loudspeakers emit sound waves along the x-axis. The sound has maximum intensity when the speakers are 19 cm apart. The sound intensity decreases as the distance between the speakers is increased, reaching zero at a separation of 29 cm.

A girl is pedaling her bicycle at a speed of 0.10 km/min. What will her displacement be after two hours? - - - - - - - - -

You stand on a bridge above a river and drop a rock into the water below from a height of 35m (assume no air resistance)

You hear a sound at 65 dB. What is the sound intensity level if the intensity of the sound is doubled?

Which type of radioactivity is not deflected by a magnetic field?

Which of these is not a source of the shock waves that lead to protostars?

Which kind of information is known about a person if that person's DNA is in a database? A. how old the person is B. where the person was probably born C. some diseases the person might have D. whether the person is likely to commit a crime

A science teacher ran a marathon. After the race she showed her students the silver blanket she was given to keep her warm. A group of students investigated how the colour of the blanket affected how much infrared radiation is absorbed

Students asked to measure the temperature of a reaction beaker recorded the following temperatures. 103.7°C, 108.4°C, 105.8°C, 104.6°C The actual temperature is 105.1°C. Which measurement is the most precise

Two atoms that are isotopes of one another must have a different number of what? electrons neutrons protons all particles