The hummingbird shown here must beat its wings repeatedly to hover over flowers and drink nectar. what force does the beating of the hummingbird’s wings overcome?

Determine the amount of work done when a crane lifts a 100-n block form 2m above the ground to 6m above the ground

Definition: this is the weighted average of all of the isotopes of an element.

In a particular chemical reaction, the energy of the reactants is 30 kj and the energy of the products is 5 kj. 
 the maximum energy of the system is 40 kj. sketch a potential energy diagram for this reaction. make sure to label the energy of the reactants, the energy of the products, the activation energy, and the enthalpy change for the reaction.