Answer:
b. 20 sec
Explanation:
y = y₀ + v₀ t + ½ g t²
0 = 0 + (100) t + ½ (-10) t²
0 = 100t − 5t²
0 = t (100 − 5t)
t = 0, t = 20
The body lands after 20 seconds.
 
        
             
        
        
        
The velocity of pin B after rod AB has rotated through 90* is vb = 3.2549 m/s.
<h3>What is Potential and Kinetic energy?</h3>
Potential energy is the energy that is stored in any item or system as a result of its location or component arrangement. The environment outside of the object or system, such as air or height, has no impact on it. In contrast, kinetic energy refers to the energy of moving particles inside a system or an item.
mass of rod, mab = 2.4kg
mass of rod, mbc = 4kg
conservation of energy 


potential energy at position 1,

V1 = 2.5 * 9.81 * 0.18 + 4 * 9.81 * 0.18
V1 = 11.30112
kinetic energy T1 at position 1 is zero
potential energy at position 2 is zero
K.E at position 2,


= 1/3 *4 * (0.36)²
=0.10368kg m²

= 1/12 *4 * (0.6)²
=0.12kg m²
on putting the values in above equation we get,
T₂ = 1.0667vb²
0 + 11.30112 = 1.0667vb² + 0
vb = 3.2549 m/s
to learn more about Kinetic and potential energy go to - brainly.com/question/18963960
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Newton's first law of motion states that an object at rest tends to stay at rest, while an object in motion tends to stay in motion unless an external force acts upon it. This law appears in basketball when the player is shooting the ball. When the player is holding the ball, the ball is at rest but when a player shoots the ball, they use force to throw the ball in the hoop.
 
        
             
        
        
        
Answer:
Yes
Explanation:
Yes. The momentum is the same when the speed of the tennis ball is 18 times greater than the speed of the basketball and the velocities of both objects are in the same direction.
 
        
             
        
        
        
Because 'acceleration' does NOT mean 'speeding up'.  
It means ANY change in motion ... speeding up, slowing down, 
or changing DIRECTION.
When traveling a roundabout, or any curved path, the direction
is constantly changing even if the speed is constant, so there is 
constant acceleration going on.