Question 1: Define kinetic energy and state the formula used to calculate it.

Answer: Kinetic energy is the energy possessed by a moving object, calculated using the formula KE = ½ mv², where m is mass in kilograms and v is velocity in metres per second.

Question 2: Explain how an increase in velocity affects the kinetic energy of an object.

Answer: Since kinetic energy is proportional to the square of velocity, increasing velocity results in a quadratic increase in kinetic energy.

Question 1: A car with a mass of 1500 kg is travelling at 20 m/s. Calculate its kinetic energy.

Answer: Kinetic energy = ½ × 1500 kg × (20 m/s)² = ½ × 1500 × 400 = 300000 Joules

Question 2: A bicycle with a mass of 15 kg is moving at 10 m/s. What is its kinetic energy?

Answer: Kinetic energy = ½ × 15 kg × (10 m/s)² = ½ × 15 × 100 = 750 Joules

Question 1: Describe a simple experiment to investigate how the kinetic energy of a rolling ball depends on its velocity. Include variables to be controlled and safety precautions.

Answer: One experiment involves rolling a ball down an inclined plane and measuring its velocity at the bottom using a motion sensor or stopwatch and a metre rule. Variables to control include the mass of the ball (keeping it constant), the angle of the incline, and the surface type. Safety precautions involve ensuring the area is clear of obstacles, handling equipment carefully to prevent injuries, and wearing safety goggles if necessary.

Question 2: Identify two variables that could affect the kinetic energy of a moving object in a practical experiment and explain how they influence the results.

Answer: Variables include the mass of the object, where increasing mass increases kinetic energy; and the velocity, where higher velocity results in higher kinetic energy.

Question 1: A skateboarder with a mass of 70 kg is travelling at 8 m/s downhill. The skateboarder then accelerates to 12 m/s. Calculate the change in kinetic energy and discuss what this indicates about energy transfer.

Answer: Initial KE = ½ × 70 kg × (8 m/s)² = ½ × 70 × 64 = 2240 Joules; Final KE = ½ × 70 kg × (12 m/s)² = ½ × 70 × 144 = 5040 Joules; Change in KE = 5040 - 2240 = 2800 Joules. This increase indicates energy gained from potential energy converted during the descent.

Question 1: Explain how understanding kinetic energy is important in designing safety features such as seat belts and airbags in vehicles.

Answer: Understanding kinetic energy helps engineers design safety features that absorb or reduce the energy during collisions. Seat belts and airbags work by increasing the time over which the vehicle's change in momentum occurs, thereby reducing the force exerted on occupants and minimizing injuries caused by high kinetic energy during impacts.