Laser beams are sometimes used to burn away cancerous tissue. What is the intensity, in watts per square meter, of a laser beam that is 90.0% absorbed by a 1.8-mm diameter spot of cancerous tissue and must deposit 475 J of energy to it in a time period of 3.95 s?

Crowbar of 5 metre is used to lift an object of 800 metre if the effort arm is 200cm calculate the force applied

Could someone me find the answer to this problem.

Which of the following situations is impossible? a) an object has velocity directed east and acceleration directed east. b) an object has zero velocity but non-zero acceleration. c) an object has constant non-zero velocity and changing acceleration. d) an object has velocity directed east and acceleration directed west. e) an object has constant non-zero acceleration and changing velocity.