Global challenges Study Guide

Deceleration refers to the rate at which an object slows down, which is essentially negative acceleration. According to Newton's Second Law of Motion, the force acting on an object is directly proportional to its mass and its acceleration (F = ma). This means that a large deceleration, especially when combined with a significant mass, will result in a large impact force. When a person or an object experiences a large deceleration, for example, during a sudden stop in a vehicle, the internal organs and skeletal structure continue to move forward due to inertia. The large force required to stop these internal parts can cause severe damage. This is why safety features in vehicles, such as seatbelts and airbags, are designed to increase the time over which the deceleration occurs. By increasing the collision time, the average force exerted on the occupant is reduced, lessening the severity of injuries. Without these features, rapid deceleration can lead to injuries like whiplash, fractures, internal bleeding, and concussions, as the body's tissues are not designed to withstand such high forces over very short durations.

The way societies use energy resources changes over time, displaying distinct patterns and trends. Historically, the primary energy sources were bio-fuels (like wood) and animal power. With the Industrial Revolution, fossil fuels such as coal became dominant due to their high energy density and ease of transport. Later, oil and natural gas rose significantly because of their versatility and efficiency in powering transport and heating homes. These historical trends show a shift towards more concentrated energy sources that could fuel industrial growth and urbanisation. Current trends indicate a growing move towards renewable energy sources like solar, wind, hydroelectric, and geothermal power. This shift is driven by increasing environmental concerns about climate change, the finite nature of fossil fuel reserves, improvements in renewable energy technologies, and government policies promoting sustainable development. However, the exact mix of energy resources used varies considerably between countries, influenced by their natural resource endowments (e.g., access to oil, coal, suitable sites for wind farms or hydroelectric dams), economic development level (developed countries can afford to invest more in new technologies), political stability, and public opinion. For example, a country with abundant sunshine might invest heavily in solar power, while another with extensive coastlines might focus on wind energy. Reliable and affordable energy is crucial for economic growth and societal well-being, so decisions about energy resource use involve balancing economic, environmental, and social factors. The overall pattern is a gradual transition from traditional, unsustainable sources to cleaner, more renewable alternatives, though the pace and specific pathways differ globally.