Final answer:
The claim that upward arrows on a cash flow diagram indicate negative cash flow is False; upward arrows represent positive cash flow, such as incomes or receipts, and downward arrows typically indicate expenses or payments.
Step-by-step explanation:
The statement that on a cash flow diagram, the vertical arrows pointing upwards represent a negative cash flow is False. Typically, in a cash flow diagram, upward arrows indicate positive cash flow, which represents receiving money or an income, while downward arrows indicate negative cash flow, which represents money being paid out or an expense.
Considering the Keynesian cross diagram and the Circular Flow Model, they provide visual representations of economic activity. In these diagrams, the convention might be different. For example, in the Keynesian cross diagram, upward motion can represent positive growth in national income or aggregate expenditure. However, we must adhere to the specific conventions used in a cash flow diagram, where upward arrows usually stand for positive cash flow, such as profits, income, or other types of cash inflow.