No se ha da han dicho nada más de lo dicho y han ido de vuelta y han dicho nada más de que se pueda hacer el favor del niño
Answer:
20cm
Explanation:
A convex lens has a positive focal length and the object placed in front of it produce both virtual and real image <em>(image distance can be negative or positive depending on the nature of the image</em>).
According to the lens equation
where;
f is the focal length of the lens
u is the object distance
v is the image distance
If the magnification is - 0.6
mag = v/u = -0.5
v = -0.5u
since v = 10cm
10 = -0.5u
u = -10/0.5
u =-20 cm
Substitute u = -20cm ( due to negative magnification)and v = 10cm into the lens formula to get the focal length f

Hence the focal length of the convex lens is 20cm
Answer:



Explanation:
g = Acceleration due to gravity = 
= Angle of slope = 
v = Velocity of child at the bottom of the slide
= Coefficient of kinetic friction
= Coefficient of static friction
h = Height of slope = 1.8 m
The energy balance of the system is given by

The speed of the child at the bottom of the slide is 
Length of the slide is given by


The force energy balance of the system is given by

The coefficient of kinetic friction is
.
For static friction

So, the minimum possible value for the coefficient of static friction is
.
The moon does not have its own light.
Answer:
Explanation:
The horizontal component of force applied = 7.97 cos 26.2 = 7.15 N.
Vertical component in upward direction = 7.97 sin 26.2 = 3.52 N.
Since the body is moving with uniform velocity, friction force will equalize the external horizontal component = 7.15 N.
So frictional force = 7.15 N.
a) Work done by rope force per second = force in horizontal direction x displacement per second = 7.15 x 4.33 = 30.95 J
b) Increase in thermal energy per second will be due to negative work done by frictional force = work done by external force = 30.95 J.
c) Normal force acting downwards = weight - vertical component of external force = 4.36 x 9.8 - 3.52 = 39.21 N
coefficient of friction = friction force / normal force = 7.15 / 39.21 = 0.18