How long is an object in the air?

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In summary, the problem is about a kangaroo jumping to a height of 2.7m and the question is asking for the time it took to reach that height. The correct equation to use is v^2 = u^2 + 2*a*s, where v is the final velocity, u is the initial velocity, a is the acceleration and s is the displacement. By using this equation, you can find the initial velocity of the kangaroo and then calculate the time it took to reach the maximum height.
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soicuw
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Homework Statement


I'm having trouble with questions such as: A kangaroo jumps to a vertical height of 2.7m. How long was it in the air before returning to earth?

Homework Equations


My guess is: vf2=2a(delta)x
but I am not certain.

The Attempt at a Solution


vf2=2*-9.8*2.7
it gave the wrong answer. The answer key says t=1.5sec. I need to know how to find this! Thanks
 
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  • #2
Hi,
You find the incorrect velocity based on your attempt.
the equation used is v^2 = u^2 + 2*a*s, where v = final velocity, u = initial velocity, a = acceleration and s = displacement.
so at maximum height, v = 0 , s = 2.7 and a = -9.8 .
then you will be able to find your initial velocity of the kangaroo, u.

after that just find the time, which i think should be easy.
 

1. How does air resistance affect the time an object spends in the air?

Air resistance can significantly impact the amount of time an object stays in the air. Objects with a larger surface area, such as a parachute, experience greater air resistance and therefore spend more time in the air compared to objects with smaller surface areas, such as a ball.

2. Can the height at which an object is dropped affect how long it stays in the air?

Yes, the height at which an object is dropped can affect its time in the air. The higher the starting height, the longer the object has to fall, and therefore, the longer it will stay in the air. This is due to the acceleration of gravity, which causes objects to fall faster the longer they are in the air.

3. How does the mass of an object impact the time it spends in the air?

The mass of an object does not have a significant effect on the time it spends in the air. In the absence of air resistance, all objects will fall at the same rate regardless of their mass. However, in the presence of air resistance, objects with larger masses may fall slightly faster due to their greater force of gravity.

4. Can the angle at which an object is launched affect its time in the air?

Yes, the angle at which an object is launched can impact its time in the air. The optimal angle for maximum time in the air is 45 degrees, as this allows for the most balanced distribution of horizontal and vertical motion. Launching an object at a higher or lower angle will result in a shorter time in the air.

5. How can we calculate the time an object spends in the air?

The time an object spends in the air can be calculated using the equation t = 2 * (v*sinθ)/g, where t is the time, v is the initial velocity, θ is the launch angle, and g is the acceleration due to gravity. This equation assumes no air resistance and a constant acceleration due to gravity of 9.8 m/s^2.

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