Answer:
x = 45 cm
Explanation:
Given that,
The length of a rod, L = 50 cm
Mass, m₁ = 0.2 kg
It is at 40cm from the left end of the rod.
We need to find the distance from the left end of the rod should a 0.6kg mass be hung to balance the rod.
The centre of mass of the rod is at 25 cm.
Taking moments of both masses such that,

The distance from the left end is 40+5 = 45 cm.
Hence, at a distance of 45 cm from the left end it will balance the rod.
 
        
             
        
        
        
Answer:

Explanation:
 = Force on one side of the door by first waiter = 257 N
 = Force on one side of the door by first waiter = 257 N
 = Force on other side of the door by second waiter
 = Force on other side of the door by second waiter
 = distance of first force by first waiter from hinge = 0.567 m
 = distance of first force by first waiter from hinge = 0.567 m 
 = distance of second force by second waiter from hinge = 0.529 m
 = distance of second force by second waiter from hinge = 0.529 m 
Since the door does not move. hence the door is in equilibrium
Using equilibrium of torque by force applied by each waiter

 
        
             
        
        
        
Answer: 55 ohms
Explanation:
Given that,
Voltage of heater (v) = 110-volt 
Current drawn by heater (I) = 2.0 amperes 
resistance of the heater (r) = ?
Since voltage, current and resistance are involved, apply the formula for ohms law.
Voltage = current x resistance 
i.e v = ir
where r = v / i
r = 110 volts / 2.0 A
r = 55 ohms
Thus, the resistance of the heater is 55 ohms
 
        
             
        
        
        
Answer:
A theory changes based on new observations and testing.
Explanation:
A scientific theory is a product of multiple trials and repeated experiments. It usually follows after carefully conducting and testing the validity of the hypothesis. 
A scientific theory provides an explanation into how something behaves. 
A law just states a finding will not explain it. 
Most theories are tenable and can be improved upon when new observations and testing are carried out.