# Kinematics rock thrown up in air

• ankit arya
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.
ankit arya
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?

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...

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.

thanks i got that!

## 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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