Answer:
The tension on the string is   
 
Explanation:
From the question we are told that 
     The mass of the rock is 
        The density of the rock is  
 
         
Generally the volume of the rock is mathematically evaluated as 
           
substituting values 
         
        
The volume of the rock immersed in water is 
        
  
substituting values 
      
      
mass of water been displaced by the this volume is 
       According to Archimedes principle
     According to Archimedes principle 
=>   
      
The weight of the water displace is  
       
       
       
The actual weight of the rock is  
        
 
       
 
      
The tension on the string is 
         
 
substituting values 
         
 
         
 
 
        
             
        
        
        
Answer:
(A) The speed just as it left the ground is 30.25 m/s
(B) The maximum height of the rock is 46.69 m
Explanation:
Given;
weight of rock, w = mg  = 20 N
speed of the rock at 14.8 m, u = 25 m/s
(a) Apply work energy theorem to find its speed just as it left the ground
work = Δ kinetic energy
F x d = ¹/₂mv² - ¹/₂mu²
mg x d = ¹/₂m(v² - u²)
g x d = ¹/₂(v² - u²)
gd = ¹/₂(v² - u²)
2gd = v² - u²
v² = 2gd  + u²
v² = 2(9.8)(14.8) + (25)²
v² = 915.05
v = √915.05
v = 30.25 m/s
B) Use the work-energy theorem to find its maximum height
the initial velocity of the rock = 30.25 m/s
at maximum height, the final velocity = 0
- mg x H = ¹/₂mv² - ¹/₂mu²
- mg x H = ¹/₂m(0) - ¹/₂mu²
- mg x H = - ¹/₂mu²
2g x H = u²
H = u² / 2g
H = (30.25)² / 2(9.8)
H = 46.69 m
 
        
             
        
        
        
Answer:
There will be 1800 W power consumption in heater
Explanation:
We have given current flowing in the heater I = 15 A 
Voltage on which heater is operating V = 120 volt 
We have to find the power consumption in the heater 
We know that power consumption is given by P = VI 
So power consumption in heater = 120 × 15 = 1800 W
So there will be 1800 W power consumption in heater
 
        
             
        
        
        
I think u should follow the formulae F=MA. So I think the answer is 120N
        
             
        
        
        
Answer:
Option (c).
Explanation:
An object when when projected at an angle, will have some horizontal velocity and vertical velocity such that,

 is the angle of projection
 is the angle of projection
The horizontal component of the projectile remains the same because there is no horizontal motion. Vertical component changes at every point.
As a projectile falls, vertical velocity increases in magnitude, horizontal velocity stays the same
.