It is a common practice to put oil in a car and to change the car's oil once in while. Why do cars need oil

Which of the following is the least reliable source of background information for a scientific project? general Internet site government Internet site library reserve section scientific journal

Simon's teacher gave him a pencil at the end of week because he did so well on the spelling test. As a result, his grades continue to get better each week.

Can protons be gained or lost in an element?

A 1.11 kg skateboard is coasting along the pavement at a speed of 6.82 m/s when a 0.880 kg cat drops from a tree vertically downward onto the skateboard. What is the speed of the skateboard-cat combination? Answer in units of m/s.

How much heat is needed to raise the temperature of 100.0 g of water by 50.0°C? (Water's specific heat is 4.18 J/g•°C)

How can the speed of a mechanical wave energy be calculated

A hollow sphere of negligible mass and radius R is completely filled with a liquid so that its density is rho. You now enlarge the sphere so its radius is 2R and completely fill it with the same liquid. What is the density of the enlarged sphere?

Assume that you stay on the Earth's surface. What is the ratio of the sun's gravitational force on you to the earth's gravitational force on you? Express your answer using two significant figures.

The following three hot samples have the same temperature. The same amount of heat is removed from each sample. Which one experiences the smallest drop in temperature, and which one experiences the largest drop?

How does uniform linear motion differ from uniform circular motion?