Explanation:
Initial energy = final energy + work done by friction
PE = PE + KE + W
mgH = mgh + 1/2 mv² + W
(800)(9.8)(30) = (800)(9.8)(2) + 1/2 (800) v² + 25000
v = 22.1 m/s
Without friction:
PE = PE + KE
mgH = mgh + 1/2 mv²
(800)(9.8)(30) = (800)(9.8)(2) + 1/2 (800) v²
v = 23.4 m/s
 
        
             
        
        
        
Unscrambling
1. resting heart rate
2. overload
3. workout
4. specificity
5. cool-down
6. progression
7. warm-up
8. the last one can only be instance, but there was a typo on the paper.
        
             
        
        
        
Answer:
D) 19.8 lbs
Explanation:
1kg in household measurement is equal to 35.274 ounces. 35.274*9=317.466 ounces.
1kg is also equal to 2.205 lbs. 9*2.205=19.8416
9 kg is also equal to 9000 grams, but grams are not a part of the household measurement system
a) 9000 grams. b) 9000 ounces. c) 19.8 ounces. d) 19.8 pounds.
This leaves us with 19.8lbs
 
        
             
        
        
        
A billiard ball collides with a stationary identical billiard ball to make it move. If the collision is perfectly elastic, the first ball comes to rest after collision.
<h3>Why does the first ball comes to rest after collision ?</h3>
Let m be the mass of the two identical balls.  
u1 = velocity before the collision of ball 1 
u2 = 0 = velocity of second ball that is at rest 
v1 and v2 are the velocities of the balls after the collision. 
From the conservation of momentum, 
∴ mu1 + mu2 = mv1 + mv2
∴ mu1 = mv1 + mv2 
∴ u1 = v1 + v2 
In an elastic collision, the kinetic energy of the system before and after collision remains same.

∴  
∴ 
∴ 
₁
₂ = 0
- It is impossible for the mass to be zero. 
 - Because the second ball moves, velocity v2 cannot be zero. 
 - As a result, the velocity of the first ball, v1, is zero, indicating that it comes to rest after collision.
 
<h3>What is collision ?</h3>
An elastic collision is a collision between two bodies in which the total kinetic energy of the two bodies remains constant. There is no net transfer of kinetic energy into other forms such as heat, noise, or potential energy in an ideal, fully elastic collision.
Can learn more about elastic collision from brainly.com/question/12644900
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