A 10 kg object falls from a height of 20 m. What is its speed just before it hit
Practice Questions
Q1
A 10 kg object falls from a height of 20 m. What is its speed just before it hits the ground? (g = 9.8 m/s²)
10 m/s
14 m/s
20 m/s
28 m/s
Questions & Step-by-Step Solutions
A 10 kg object falls from a height of 20 m. What is its speed just before it hits the ground? (g = 9.8 m/s²)
Correct Answer: 19.8 m/s
Step 1: Identify the mass of the object. In this case, the mass is 10 kg, but we won't need it for this calculation.
Step 2: Identify the height from which the object falls. Here, the height is 20 meters.
Step 3: Identify the acceleration due to gravity. It is given as g = 9.8 m/s².
Step 4: Use the formula for speed just before hitting the ground, which is v = √(2gh).
Step 5: Substitute the values into the formula: v = √(2 * 9.8 * 20).
Step 6: Calculate the value inside the square root: 2 * 9.8 * 20 = 392.
Step 7: Take the square root of 392 to find v: v = √392.
Step 8: Calculate √392, which is approximately 19.8 m/s.
Conservation of Energy – The principle that the total energy in a closed system remains constant; in this case, potential energy is converted to kinetic energy as the object falls.
Kinematics – The study of motion, which includes understanding how speed and acceleration relate to distance and time.