If a 10 kg object is dropped from a height of 20 m, what is the velocity just be

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Question: If a 10 kg object is dropped from a height of 20 m, what is the velocity just before it hits the ground? (Assume g = 10 m/s²) (2019)

Options:

Correct Answer: 20 m/s

Exam Year: 2019

Solution:

Using v² = u² + 2gh, v = √(0 + 2 × 10 m/s² × 20 m) = √400 = 20 m/s.

If a 10 kg object is dropped from a height of 20 m, what is the velocity just before it hits the ground? (Assume g = 10 m/s²) (2019)

If a 10 kg object is dropped from a height of 20 m, what is the velocity just before it hits the ground? (Assume g = 10 m/s²) (2019)

Step 1: Identify the initial velocity (u) of the object. Since the object is dropped, u = 0 m/s.
Step 2: Identify the acceleration due to gravity (g). We are given g = 10 m/s².
Step 3: Identify the height (h) from which the object is dropped. Here, h = 20 m.
Step 4: Use the formula v² = u² + 2gh to find the final velocity (v) just before the object hits the ground.
Step 5: Substitute the values into the formula: v² = 0 + 2 × 10 m/s² × 20 m.
Step 6: Calculate the right side: 2 × 10 × 20 = 400.
Step 7: Now, v² = 400, so take the square root of both sides to find v: v = √400.
Step 8: Calculate the square root: v = 20 m/s.

Kinematics – The question tests the understanding of kinematic equations, specifically the relationship between initial velocity, final velocity, acceleration, and displacement.
Gravitational Acceleration – It assesses the knowledge of gravitational acceleration and its effect on falling objects.