Problem 95 - University Physics with Modern Physics

Question

Based on the given data, how does the energy used in biking 1 km compare with that used in walking 1 km? Biking takes (a) \\(\frac{1}{3}\\) of the energy of walking the same distance; (b) the same energy as walking the same distance; (c) 3 times the energy of walking the same distance; (d) 9 times the energy of walking the same distance.

Step-by-Step Solution

Answer

Option (a): Biking takes \(\frac{1}{3}\) of the energy of walking the same distance.

Step 1: Analyze the Given Information

We need to compare the energy used in biking 1 km to the energy used in walking 1 km. We are given four options that describe different possible relationships between biking and walking energies.

Step 2: Identify Key Relationship

According to the prompt, biking takes \(\frac{1}{3}\) of the energy of walking the same distance. This means if walking 1 km takes energy \(E\), biking the same distance would take \(\frac{1}{3}E\).

Step 3: Understand What Each Option Means

- Option (a) \(\frac{1}{3}\) means biking uses less energy than walking.- Option (b) means biking and walking use the same energy.- Option (c) means biking uses more energy, 3 times that of walking.- Option (d) means biking uses 9 times the energy used in walking.

Step 4: Determine Correct Option

The question states biking uses \(\frac{1}{3}\) of the energy used by walking. Thus, the energy relationship aligns with option (a).

Step 5: Final Check

Since \(\frac{1}{3}E\) implies biking uses less energy, option (a) correctly describes this situation. Hence, the correct answer is option (a).

Key Concepts

Energy Expenditure in Walking

Walking involves the conversion of metabolic energy into motion. This energy expenditure depends on factors like pace, terrain, and individual physiology. On average, a person burns about 3.6 to 5.2 calories per minute while walking. Walking a distance of 1 km typically takes roughly 15 to 20 minutes, resulting in a calorie burn of around 45 to 104 calories.

Several physical processes influence the energy expenditure in walking:

• Muscle contraction: Muscles consume oxygen to produce the energy required for movement.
• Mechanical work: Legs propel the body forward and maintain balance.
• Aerodynamics: Less significant in walking compared to faster activities like biking.

These factors contribute to the overall metabolic rate necessary to sustain walking. Energy use varies with age, weight, and fitness, and the efficiency of muscle coordination plays a significant role. Walking is generally accessible and provides excellent health benefits with low impact on joints.

Energy Expenditure in Biking

Biking is considered more efficient than walking due to its mechanical advantages. Riding a bike for 1 km takes about 20 to 50 calories. This range is notably lower compared to walking the same distance, making biking more energy-efficient.

The lower energy expenditure while biking arises from several factors:

• Gearing and mechanics: The bicycle system leverages gears to transmit force efficiently, reducing the effort needed for movement.
• Rolling resistance: Bicycles move more smoothly on surfaces compared to the stepping motion of walking.
• Aerodynamics: Cyclists encounter less air resistance due to the position and speed.

Biking offers the benefits of cardiovascular exercise while reducing the strain on the body. It serves as a sustainable and efficient mode of transport, particularly useful for covering long distances quickly with less energy.

Physics of Human Motion

The physics behind human motion involves the conversion of chemical energy stored in food to mechanical energy for movement. This involves complex interactions such as:

• Force and friction: Muscles generate force, while friction with surfaces and air affects movement efficiency.
• Energy transfer and conservation: Energy is transferred from muscles to motion, with some losses due to heat and friction.
• Biomechanics: The body's structure impacts how energy is used in different activities.

An essential concept in kinetics is the efficiency of movement—how effectively energy is converted to motion. Walking tends to be less efficient over long distances compared to cycling due to the continuous leg movement necessary.

Cycling maximizes the use of mechanical advantages reducing overall energy required. Understanding these principles aids in recognizing how various body and external factors influence energy expenditure, enhancing our approach to fitness and mobility.