What Elevation Angle Clears the Wall and Hits the Target?

AI Thread Summary
To determine the appropriate elevation angle for a projectile to clear a 10 m high wall and hit a target 28.9 m away, initial calculations suggest an angle of 44 to 45 degrees, but the correct angle is closer to 65 degrees. The projectile's initial speed is 20 m/s, and the wall is positioned halfway to the target. Using the equations of motion, the calculations show that while the 44-degree angle allows the projectile to clear the wall, it falls short of reaching the target by nearly 12 meters. Adjusting the angle is necessary to ensure both the wall is cleared and the target is hit. Therefore, further analysis and adjustments to the angle are essential for achieving the desired outcome.
rsmseys
Messages
4
Reaction score
0

Homework Statement



A projectile, initial speed v = 20 m/s is supposed to hit a target D = 28.9 m away. However an H = 10 m high wall is placed halfway between the launching point and the target. What is the appropriate elevation angle? (in degrees).

Homework Equations



http://en.wikipedia.org/wiki/Equations_of_motion#Equations_of_uniformly_accelerated_linear_motion

The Attempt at a Solution



I got the answer of around 44 to 45 degrees. The correct answer is said to be closer to 65 degrees. Any help in clarifying which answer is right would be helpful, along with solutions. Thanks.
 
Physics news on Phys.org
and how did you reach your answer?

According to PF rules no solns can be given... just help or advice.
 
v = at
20sin(x) = 9.8t
20sin(x) / 9.8 = t
s = 1/2(u +v)t
10 = 1/2 * (20sin(x))*(20sin(x))/9.8

Solving for x, the answer for x (the angle) is 44.427 degrees.
 
Not quite, but you're on the right track.

Work it backwards with your result and you'll see that although you just cleared the wall, you missed the target by nearly 12m.
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'Calculation of Tensile Forces in Piston-Type Water-Lifting Devices at Elevated Locations'

Thread 'Calculation of Tensile Forces in Piston-Type Water-Lifting Devices at Elevated Locations'

Figure 1 Overall Structure Diagram Figure 2: Top view of the piston when it is cylindrical A circular opening is created at a height of 5 meters above the water surface. Inside this opening is a sleeve-type piston with a cross-sectional area of 1 square meter. The piston is pulled to the right at a constant speed. The pulling force is（Figure 2）： F = ρshg = 1000 × 1 × 5 × 10 = 50,000 N. Figure 3: Modifying the structure to incorporate a fixed internal piston When I modify the piston...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Projectile Motion -- Help please understanding these basic problems
Replies
4
Views
1K
Projectile Motion - object that is shot at an angle of 55 degrees
Replies
8
Views
2K
Calculating angle of projectile to hit target
Replies
2
Views
3K
Projectile motion of a cannon ball versus time
Replies
15
Views
2K
Projectile Motion (Ball thrown towards a wall)
Replies
8
Views
6K
What Are the Optimal Launch Angles for a Projectile to Pass Through an Opening?
Replies
25
Views
3K
How Long to Reach Maximum Height for a 70 m/s Projectile at 45 Degrees?
Replies
5
Views
2K
Projectile motion with only distance, an angle and a ratio
Replies
22
Views
2K
Projectile Motion Experimental Error
Replies
1
Views
2K
Calculate the displacement? (Projectile motion problem)
Replies
3
Views
2K

Hot Threads

Recent Insights

Back
Top