Which of the following is an example of a chemical change?

melting a stick of butter

dissolving salt in water

using magnesium to displace hydrogen gas from water

Starting from rest, a 4.0-kg body reaches a speed of 8.0 m/a in 20 s. What is te net force acting on the body?

Suppose that a person has an average heart rate of 72.0 beats/min. How many beats does he or she have in 2.0 y? In 2.00 y? In 2.000 y?

Light enters an equilateral triangle prism in a direction parallel to one side. The prism is made of glass with an index of refraction of 1.52. What is the angle between the incoming ray and the ray that leaves the prism on the other side?

Many dogs have ticks and fleas in their fur. Ticks and fleas feed upon the blood of dogs to get nutrients is that competition, parasitism, mutualism or commensalism

if a man weighs 900N on earth, what is his weight on jupiter where the acceleration due to gravity is 25.9 m/s^2?

During a demonstration of the gravitational force on falling objects to her class, Sarah drops an 11 lb. bowling ball from the top of the science building. Determine distance the ball has traveled after falling for 1.

A teacher wants to demonstrate that unheated water can boil at room temperature in a beaker within a bell jar connected to a vac-uum pump. However, the vacuum pump is faulty and can reduce pressures only to 15 kPa.

How many btus of heat energy are needed to raise the temperature of 99.6 lbs of water from 50 °f to 130 °f?

What is a different form of a characteristic, such as brown hair, is called

A book falls of the table and hits the floor. Is work done? Why?