Answer:
20 J
Explanation:
Kinetic energy is given as half of the product of mass and the square of velocity of an object:
KE = 
where m = mass = 40 kg
v = velocity = 1 m/s
Hence, Mary's kinetic energy is:
KE = 
KE = 20 * 1 = 20 J
She has a kinetic energy of 20 J.
 
        
             
        
        
        
D. Advances in technology were needed to gather more evidence.
Explanation:
New technologies had to be developed to ascertain Wegener's claims. 
The major flaw in Wegener's postulate was that the moving continents lacked a mechanism to drive them into motion. 
His theory needed more scientific backing also. 
- A major leap was made when new technologies used during the second world war was deployed to investigate the ocean floor. 
- Sequences of magnetic anomalies were unraveled using equipment developed during the second world war 
- This gave further proof to the idea of continental drift and it expanded the theory into a more broader and inclusive theory of plate tectonics. 
Learn more: 
Wegener brainly.com/question/5002949
#learnwithBrainly
 
        
             
        
        
        
Answer:
ax = -3.29[m/s²]
ay = -1.9[m/s²]
Explanation:
We must remember that acceleration is a vector and therefore has magnitude and direction.
In this case, it is accelerating downwards, therefore for a greater understanding we will make a diagram of said vector, this diagram is attached.
![a_{x}=-3.8*cos(30) = -3.29 [m/s^{2}]\\ a_{y}=-3.8*sin(30) = -1.9 [m/s^{2}]](https://tex.z-dn.net/?f=a_%7Bx%7D%3D-3.8%2Acos%2830%29%20%3D%20-3.29%20%5Bm%2Fs%5E%7B2%7D%5D%5C%5C%20a_%7By%7D%3D-3.8%2Asin%2830%29%20%3D%20-1.9%20%5Bm%2Fs%5E%7B2%7D%5D)
 
        
             
        
        
        
The one that both benefits each other is the one I think it's mutalistic