Projectile motion and trajectory

In summary, the problem involves a car being driven off a cliff at 8 m/s and landing in the sea 3 seconds later. The question asks for the distance it lands, the height of the cliff (given that g = 10m/s^2), and the angle at which it lands relative to the horizontal. Using the equations for horizontal and vertical components, the car is found to have traveled a distance of 24m and landed at a height of -45m. The final velocity is calculated to be -29.4m/s, and the angle can be determined using the components of the velocity vector.
  • #1
Alvl tay
3
0

Homework Statement



A car is drove off a cliff at 8 m/s. it lands in the sea 3 seconds later.

Homework Equations



a) how far does it land?
b)how high is the cliff? (g = 10m/s^2)
c) at what angle relative to the horizontal does it land?

The Attempt at a Solution


convention chosen : upwards is positive
initial velocity= 0m/s
a= -g
Vx=8m/s

a) FROM HORIZONTAL COMPONENT

Vx= x(displacement)/ t( time)
8m/s = x/3s
x=24m

b) FROM VERTICAL COMPONENT
using the eq'n s=ut + 0.5at^2
ie. y = 0.5 gt^2

y = 0.5 (-10)(9)
y= - 45 m

c) ** my problem is that I am not sure which eq'n to use

since its relative to the horizontal there is only one... i think.

Vx = Vt cosθ
i have t= 3s
i have x=24m
i don't have V ,or at least i don't know what V exactly is.

Help please?:confused:
 
Last edited:
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  • #2
It will be clear if you make a drawing indicating the initial and final positions of the car. You need the angle of the displacement vector, not the angle of the initial velocity which is horizontal.

ehild
 
  • #3
The x-component of the velocity is just the initial 8m/s.The final velocity of a uniformly accelerated object is
Vf=Vi+gt=0+(-9.8m/s^2)*3s=-29.4m/s
which is the y-component.

Then the angle should be the angle made up from those vector components: tan(8/24), or is it tan(24/8), can't think straight about it at the moment.
 
  • #4
i solved it already :/ a long time ago.
am i supposed to delete the post then?
 
  • #5
Alvl tay said:
i solved it already :/ a long time ago.
am i supposed to delete the post then?

You should have written that the problem was solved.

ehild
 
Last edited:

1. What is projectile motion?

Projectile motion is the motion of an object that is projected into the air at an angle, and then moves along a curved path under the influence of gravity.

2. What factors affect the trajectory of a projectile?

The trajectory of a projectile is affected by the initial velocity, the angle of projection, and the force of gravity. Other factors such as air resistance and wind can also play a role.

3. How is the range of a projectile calculated?

The range of a projectile is the horizontal distance it travels before hitting the ground. It can be calculated using the equation: range = (initial velocity)^2 * sin(2θ) / g, where θ is the angle of projection and g is the acceleration due to gravity.

4. What is the difference between horizontal and vertical velocity in projectile motion?

Horizontal velocity is the component of velocity that is parallel to the ground, while vertical velocity is the component of velocity that is perpendicular to the ground. In projectile motion, the horizontal velocity remains constant while the vertical velocity changes due to the influence of gravity.

5. Can the trajectory of a projectile be affected by external forces?

Yes, external forces such as air resistance, wind, and friction can affect the trajectory of a projectile. These forces can cause the projectile to deviate from its expected path and can also impact its range and final landing point.

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