It's very tough to use the drop-down menus for this. I'll just do the best I can without them.
-- Objects with the same charge repel each other with electrostatic force, and attract each other with gravity. You can ignore the gravity because the electrostatic force is so much stronger.
-- Objects with opposite charge attract each other with electrostatic force, and also attract each other with gravity. You can ignore the gravity because the electrostatic force is so much stronger.
-- Objects with no charge have no electrostatic force between them, and they only attract each other with gravity.
There will not be enough momentum from the first hill to cross another hill if he same or larger size because of the way potential energy and kinetic energy works it will not be able go as high as it could go on he fist hill.
Answer:
To unlock a door and indicate to the person that the door is now unlocked
Explanation:
Schools all have doors locked. Visitors/parents need to press a button. That creates a buzz sound in the office, secretary presses a button to unlock the door. The person trying to enter the school hears a buzz and the secretary telling them to enter the building.
Answer:
Explanation:
Given
Velocity of Huck w.r.t to raft 
Perpendicular to the motion of raft
Velocity of Raft in the river 
As Huck is traveling Perpendicular to the raft so he possess two velocities i.e. vertical velocity and horizontal velocity of River when observed from bank
So magnitude of velocity is given by
For direction 
w.r.t river bank
