A projectile is thrown horizontally from a 490m high cliff with a velocity of 100 ms-1. The time taken by the projectile to reach the ground is:
Correct answer: D. 10 s
- A. 2.5 s
- B. 5.0 s
- C. 7.5 s
- D. 10 s
Explanation
The following is the solution: We will use the equation: h = (1/2)gt2 where: h = vertical distance fallen (in this case, the height of the cliff = 490 m), g = acceleration due to gravity (approximately 9.8 m/s² on Earth's surface), and t = time taken to reach the ground. We know that the initial vertical velocity (vy) of the projectile is 0 m/s because it is thrown horizontally. The vertical component of the initial velocity is zero since there is no initial upward or downward motion. The vertical distance fallen is the height of the cliff is 490 m. Now, let's solve for time (t): 490 = (1/2) x 9.8 x t2 Divide both sides by (1/2) x 9.8: t2 = 490 / (1/2) x 9.8 t2 = 100 Take the square root of both sides: t = √100 t = 10 seconds So, the time taken by the projectile to reach the ground is 10 seconds. Hence the correct option is D.
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