Calculating Time for Javelin Throw Angle Change

[Cheddar]

Homework Statement

In the javelin throw, the javelin is launched at a speed of 29m/s at an angle of 36degrees above the horizontal. As the javelin travels upward, its velocity points above the horizontal at an angle that decreases as time passes. How much time is required for the angle to be reduced to 18degrees?

Homework Equations

I can't find anything nor have we had any problems like this before.

The Attempt at a Solution

I'm sorry to say I can't even begin this problem. Anything that would point me in thr right direction would be great.

 

[tms]

Figure out the vertical speed from the initial speed and the angles. Then use the kinematics equations to find out when the vertical speed would decrease to the speed you calculated.

 

[tomcue]

As a scientist, it is important to have a strong understanding of physics principles and equations in order to solve problems like this. In this case, the key equations to consider are the equations for projectile motion, specifically the components of velocity and acceleration in the x and y directions.

To begin, we can use the known initial velocity of the javelin (29m/s) and the angle at which it is thrown (36 degrees) to calculate the initial velocity components in the x and y directions. From there, we can use the equations for velocity and acceleration to track the changes in the javelin's angle over time.

One approach could be to set up a system of equations, with one equation for the horizontal component of velocity (Vx) and one for the vertical component of velocity (Vy). We can also set up an equation for the angle, using trigonometric functions, and solve for the time when the angle reaches 18 degrees.

Alternatively, we could also use the equation for range (horizontal distance traveled) to find the time at which the javelin's angle reaches 18 degrees. This equation takes into account the initial velocity, angle, and acceleration due to gravity.

Overall, the key is to use the known information about the javelin's initial velocity and angle to set up and solve equations that track the changes in velocity and angle over time. With a strong understanding of projectile motion, you should be able to solve this problem and any similar ones in the future.