How long is an object in the air?

  • Thread starter Thread starter soicuw
  • Start date Start date
  • Tags Tags
    Air
Click For Summary
SUMMARY

The discussion centers on calculating the time a kangaroo is in the air after jumping to a height of 2.7 meters. The correct approach involves using the kinematic equation v² = u² + 2as, where the final velocity (v) at the peak is 0 m/s, acceleration (a) is -9.8 m/s², and displacement (s) is 2.7 m. By solving for the initial velocity (u) and subsequently determining the time of flight, the correct answer is confirmed to be 1.5 seconds, as stated in the answer key.

PREREQUISITES
  • Understanding of kinematic equations in physics
  • Knowledge of gravitational acceleration (9.8 m/s²)
  • Ability to manipulate algebraic equations
  • Familiarity with concepts of displacement and velocity
NEXT STEPS
  • Study the kinematic equations in detail, focusing on their applications in vertical motion
  • Learn how to derive time of flight from initial velocity and acceleration
  • Explore examples of projectile motion to reinforce understanding of vertical jumps
  • Practice solving similar problems involving different heights and initial velocities
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone interested in mastering the principles of motion and kinematics, particularly in relation to vertical jumps and projectile motion.

soicuw
Messages
4
Reaction score
0

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
 
Last edited:
Physics news on Phys.org
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.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 6 ·
Replies
6
Views
5K
  • · Replies 16 ·
Replies
16
Views
4K
  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 1 ·
Replies
1
Views
9K
  • · Replies 15 ·
Replies
15
Views
6K
  • · Replies 7 ·
Replies
7
Views
3K