Bonjour
C'est la fille de ma mère mais ce n'est pas moi, qui est-ce ?
<em>She is my mother daughter but, she's not me ? Who is she ?</em>
<em />
<em>Ma sœur  </em><em> = my sister</em>
<em />
<em>☺☺☺</em>
 
        
             
        
        
        
Part A
Free fall motion
h = 3.1 m
Equation: Vf = √(2gh) = √(2*9.8 m/s^2 * 3.1 m) = 7.8 m/s 
That is the only part in the question.
        
             
        
        
        
Answer:
3) D: 31 m/s
4) D: 84.84 metres
Explanation:
3) Initial velocity along the x-axis is;
v_x = v_o•cos θ
Initial velocity along the y-axis is;
v_y = v_o•sin θ
Plugging in the relevant values, we have;
v_x = 31 cos 60
v_x = 31 × 0.5
v_x = 15.5 m/s
Similarly,
v_y = 31 sin 60
v_y = 31 × 0.8660
v_y = 26.85 m/s
Thus, magnitude of the initial velocity is;
v = √(15.5² + 26.85²)
v ≈ 31 m/s
4) Formula for horizontal range is;
R = (v² sin 2θ)/g
R = (31² × sin (2 × 60))/9.81
R = 84.84 m
 
        
             
        
        
        
Answer:
The time is 
Explanation:
Given that,
Capacitor = 120 μF
Voltage = 150 V
Resistance = 1.8 kΩ
Current = 50 mA
We need to calculate the discharge current
Using formula of discharge current

Put the value into the formula


We need to calculate the time
Using formula of current

Put the value into the formula





Hence, The time is 
 
        
             
        
        
        
Answer:
B.The force of friction between the block and surface will decrease.
Explanation:
The force of friction is given by 

where  is the coefficient of friction and
 is the coefficient of friction and  is the normal force.
 is the normal force.
When the student pulls on the block with force  at an angle
 at an angle  , the normal force on the block becomes
, the normal force on the block becomes 

and hence the frictional force becomes 
 .
.
Now, as we increase  ,
,  increases which as a result decreases the normal force
 increases which as a result decreases the normal force  , which also means the frictional force decreases; Hence choice B stands true.
, which also means the frictional force decreases; Hence choice B stands true. 
<em>P.S: Choice D is tempting but incorrect since the weight </em> <em> is independent of the external forces on the block. </em>
<em> is independent of the external forces on the block. </em>