What is true about coal as an energy source

What is the frequency of an ultrasound that vibrates 30 000 times a second

A probe is launched from earth and lands on mars the gravitational acceleration on mars is 3.7 m/s. Which statement best compares the mass and weight of the probe

A cage containing male mosquitoes has a small earphone placed on top, through which the sound of a female mosquito is played. all the males immediately fly to the earphone and go through all of the steps of copulation.

Two identical steel balls mounted on wooden posts initially have different amounts of charge, one with - 14uC and the other with - 2uC. the balls are allowed to touch then separated again. what is the final charge on each ball?

A glider with mass m = 0.200 kg sits on a frictionless, horizontal air track. It is connected to a spring of negligible mass and force constant k = 5.00 N/m. You pull on the glider to stretch the spring 0.100 m, and then release the glider.

Drivers are able to see objects ahead of them because light travels through windshields.

How are trade winds affected by the coriolis effect

When a raw egg gets heated into an edible egg is this considered a physical or chemical change?

Starting at its rightmost position, it takes 2 seconds for the pendulum of a grandfather clock to swing a horizontal distance of 18 inches from right to left and 2 seconds for the pendulum to swing back from left to right.

A question about a moral issue is answered by examining facts rather than opinions. is generally considered a scientific question. cannot be answered with scientific methods. cannot be debated through discussion.