Question

You've been called in to investigate a car accident by the Bluffs. A car went over a 7.93 meter high cliff
and fell so that it hit the ground 26.7 meters from the base of the cliff. The driver was lucky to walk
away with minor injuries, but the car is a write-off. He claims that he was not driving over the posted
speed limit of 9.72 m/s. For insurance purposes, determine if the driver is lying or telling the truth.

Answer 1

Explanation:

Use the height of the cliff to determine how long it took the car to land.

Take down to be positive.  Given:

Δy = 7.93 m

v₀ = 0 m/s

a = 9.8 m/s²

Find: t

Δy = v₀ t + ½ at²

7.93 m = (0 m/s) t + ½ (9.8 m/s²) t²

t = 1.27 s

Use the time to calculate the horizontal velocity.

Given:

Δx = 26.7 m

a = 0 m/s²

Find: v₀

Δx = v₀ t + ½ at²

26.7 m = v₀ (1.27 s) + ½ (0 m/s²) (1.27 s)²

v₀ = 21.0 m/s

The driver was going 21.0 m/s, faster than the speed limit of 9.72 m/s.

Answer 2

Answer:

21.0 m/s than the speed limit

Explanation:

You've been called in to investigate a car accident by the Bluffs. A car went over a 7.93 meter high cliff  and fell so that it hit the ground 26.7 meters from the base of the cliff. The driver was lucky to walk  away with minor injuries, but the car is a write-off. He claims that he was not driving over the posted  speed limit of 9.72 m/s. For insurance purposes, the driver is lying. In order to prove this you must, use the height of the cliff to determine how long it took the car to land.