A student made the table shown to list some contact and non-contact forces. Examples of Forces
Contact Forces Non-Contact Forces
The force exerted by a stretched spring The force applied by Earth and sun on each other
The electrical force exerted by a positive charge on a negative charge Magnetic attraction between two magnets

Which statement best explains why the table is incorrect?
Spring force is a force acting at a distance.
Electrical force is not a contact force.
Gravitational force can act between planets and sun only when they are in contact.
Magnetic attraction is a contact force

Asquare 1m x 1m plate is shown below. all four of its edges are kept at 0 co. at t=0the temperature distribution is given by: y xtsins n75)=.a) using separation of variables determine the temperature distribution t(x,y,t)along the plate at any time t.b) discretize the heat conduction equation +=22222 txtusing a second-order centered difference scheme for the two second derivatives and a first-order forward euler scheme for the first derivative. using von neumann stability analysis, determine the stability criterion for the proposed discretization scheme in terms of , hand t. solve for the maximum allowable time step tmax