Force is a type of Act. Force is related to Electricity. Electricity is related to Rub. Rub is related to Lamp. 
Grocery is related to Sack. you are likely to find Ball in/at/on Sack. 
Act <--IsA-- Force <--RelatedTo--> Electricity <--RelatedTo--> Rub <--RelatedTo--> Lamp 
Grocery <--RelatedTo--> Sack <--AtLocation-- Ball 