Which of these is an example of a chemical change?

a. leaving cheese out to get moldy

b. smelling sprayed perfume

c. feeling ice melt on your skin

d. crushing ice with a hammer

How much horizontal force f must a sprinter of mass 47 kg exert on the starting blocks to produce this acceleration? express your answer in newtons using two significant figures?

Can more people see a total solar eclipse or a total lunar eclipse? Explain.

Which statement best explains the movement of electric current from the clouds to the ground during a lightning storm?. A. the ground and the clouds are both negatively charged. B. the ground and the clouds are both positively charged C.

What are mechanical waves?

Radio waves are diffracted by large objects such as buildings, whereas light is not noticeably diffracted. Why is this? A. The wavelength of light is much greater than the wavelength of radio waves. B.

Find a numerical value for rhoearth, the average density of the earth in kilograms per cubic meter. Use 6378km for the radius of the earth, G=6.67*10-11m3 / (kg⋅s2), and a value of g at the surface of 9.80m/s2.

The driver of a car traveling at 32 m/s applies the brakes and undergoes a constant deceleration of 2.25 m/s^2.

The ability of an object to vibrate by absorbing energy at its natural frequency is called?

A hurricane in the Gulf of Mexico to 15 hours to travel 360 kilometers. What is the average speed of this hurricane in kilometers per hour?

Which organization functions to privide clinics and surgeries i developing nations