Kinematics rock thrown up in air

In summary, the velocity of a rock thrown upward on the planet Mars can be calculated using the equation H = 22t - 1.86t^2, where t represents time in seconds. The velocity of the rock at a specific time t can be found by substituting t for a in the equation V = 22 - 3.72a. The rock will hit the surface after 11.83 seconds and will have a velocity of 0 m/s.
  • #1
ankit arya
2
0
kinematics ... rock thrown up in air

Homework Statement




If a rock is thrown upward on the planet Mars with a velocity of 22 m/s, its height (in meters) after t seconds is given by H = 22t - 1.86t^2.
Find the velocity of the rock when t = a.
When will the rock hit the surface?
With what velocity will the rock hit the surface?

Homework Equations


v=u+at



The Attempt at a Solution


i found the ans for first two ques but i am not able to solve the third one.

velocity at t=a is 22-3.72a
rock will hit the surface at t=11.83s

pls help me with the third one...
 
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  • #2


Welcome to PF.

Gravity is a conservative field. So at the same height going up ...

|Vinitial| = |Vfinal|

... going down.

Or you could do it the long way and evaluate

V = Vinitial - a*t

Using the total time of flight.
 
  • #3


thanks i got that!
 

Related to Kinematics rock thrown up in air

What is kinematics?

Kinematics is a branch of physics that studies the motion of objects without considering the forces that cause the motion.

What is the equation for calculating the maximum height of a thrown rock?

The equation for calculating the maximum height of a thrown rock is h = (v^2 * sin^2θ)/(2g), where h is the maximum height, v is the initial velocity, θ is the angle of projection, and g is the acceleration due to gravity.

How does air resistance affect the motion of a thrown rock?

Air resistance can reduce the maximum height and distance traveled of a thrown rock, as it acts in the opposite direction of the motion and slows down the rock.

What is the difference between projectile motion and vertical motion?

Projectile motion refers to the motion of an object in a parabolic path, while vertical motion refers to the motion of an object in a straight line in the vertical direction.

Can the initial velocity of a thrown rock be negative?

Yes, the initial velocity of a thrown rock can be negative if it is thrown downwards or in the opposite direction of the positive y-axis. This would result in a negative value for the maximum height and a downward parabolic path for the rock.

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