Finding the Initial Speed of a Blue Car in a Projectile Motion Scenario

In summary, the blue car's reaction time was 2/3 of a second and it hit the red car at the bottom of a hill with an angle of 2 degrees. The length of the skid marks was 60m and the pizza sign traveled 11m before hitting the ground. The coefficient of friction between the blue car's tires and the ground is .75 and the height of the car is 1.47m. To find the car's initial speed, the time it takes for the pizza sign to hit the ground needs to be calculated using its initial velocity.
  • #1
Joel M
4
0

Homework Statement


A blue car carrying a pizza sign goes over a hill and sees a red car stopped at the bottom. The blue car is unable to stop in time and hits the red car, sending the pizza sign flying.

The blue car's reaction time is 2/3 of a second.
The length of the skid marks from the point which the blue car started braking to the point where it hit the red car is 60m.
The sign traveled 11m before hitting the ground.
The coefficient of friction between the blue car's tires and the ground is .75.
The height of the car is 1.47m.
The angle of the hill is 2 degrees.
Find the car's initial speed.

(Assume that the cars crashed on a level surface, assume the red car did not move, and assume that the pizza sign was not mounted on the car. Acceleration of gravity is 9.8m/s^2. Disregard air resistance.)

Homework Equations


Vf^2 = Vi^2 * 2a * deltaX?
I'm sure there is more, but I first need to figure out where to start.

The Attempt at a Solution


I drew up this diagram in photoshop and uploaded it to flickr:
4074346500_5535009bd5_o.jpg


I decided to first find the time that it takes for the sign to hit the ground. I then broke up the signs properties into x and y components. I used the equation listed above to find final velocity in the y direction which came out to be 5.36m/s. I am now stuck. I'm not even sure that I started it correctly. Any help from here would be greatly appreciated!
 
Last edited:
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  • #2
The pizza sign is a clue to how fast the car was traveling when it hit the red car. Therefore you need to find its initial velocity.
 
  • #3
That's what I am trying to do. Once I get further I will update this thread. Thanks.
 

1. What is projectile motion?

Projectile motion is a type of motion in which an object is thrown or launched into the air and moves along a curved path under the influence of gravity.

2. What factors affect projectile motion?

The factors that affect projectile motion include the initial velocity, angle of launch, air resistance, and the force of gravity.

3. How is the trajectory of a projectile calculated?

The trajectory of a projectile can be calculated using the equations of motion, which take into account the initial velocity, angle of launch, and acceleration due to gravity.

4. Can a projectile have a parabolic trajectory?

Yes, a projectile's trajectory is typically parabolic in shape due to the influence of gravity. However, air resistance and other external factors can cause deviations from a perfect parabolic path.

5. How does increasing the angle of launch affect the range of a projectile?

Increasing the angle of launch will generally increase the range of a projectile, reaching its maximum when launched at a 45-degree angle. However, if the angle is too high, the projectile may not have enough horizontal velocity to overcome the downward pull of gravity and will fall short of its maximum range.

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