Acceleration of rock due to gravity

In summary, to find the velocity of a rock dropped from rest at the top of a 125 cm high cliff, you can use the equation v = u + at where u is the initial velocity (which is 0 since it's dropped from rest) and a is the acceleration due to gravity (9.81 ms). To find the velocity, you can either use conservation of energy or another kinematic equation that involves velocity, distance and acceleration. The resulting velocity is 49.5 ms. Additionally, the time it takes for the rock to strike the ground can be found using the same equation, and is equal to 5.05 ms.
  • #1
WhyDidItakeIt
1
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A rock is dropped from rest at the top of a cliff 125 cm high.

a) At what speed does it strike the ground?

b) How long does it take?



To find the velocity the equation used is v = u + at

I know that (u = 0) as it's from rest and g = 9.81 ms (gravity)

But I just need help on how to get the velocity when the time is not stated!

I have the answers but I'm not sure how to reach them

a) 49.5 ms

b) 5.05 ms
 
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  • #2
You have two options:

(1) Use conservation of energy

(2) Use another kinematic equation which involves velocity, distance and acceleration
 

1. What is acceleration of rock due to gravity?

The acceleration of rock due to gravity is the rate at which a rock falls towards the ground under the influence of gravity. This acceleration is approximately 9.8 meters per second squared (m/s²) on Earth.

2. How is acceleration of rock due to gravity calculated?

The acceleration of rock due to gravity can be calculated using the formula a = g, where "a" represents acceleration and "g" represents the gravitational constant, which is approximately 9.8 m/s² on Earth.

3. Does the mass of the rock affect its acceleration due to gravity?

Yes, the mass of the rock does affect its acceleration due to gravity. According to Newton's Second Law of Motion, the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass. This means that a heavier rock will experience a greater force of gravity and therefore have a greater acceleration towards the ground.

4. How does the acceleration of rock due to gravity change with distance from Earth's surface?

The acceleration of rock due to gravity decreases as the distance from Earth's surface increases. This is because the force of gravity is inversely proportional to the square of the distance between two objects. In other words, the further away the rock is from Earth's surface, the weaker the force of gravity and therefore the slower the acceleration towards the ground.

5. Is the acceleration of rock due to gravity constant on all planets?

No, the acceleration of rock due to gravity varies on different planets depending on their mass and radius. For example, the acceleration of rock due to gravity on Mars is approximately 3.7 m/s², while on Jupiter it is approximately 24.8 m/s². This is because the gravitational constant is different on each planet due to their varying masses and sizes.

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