The doctor's average speed for the whole trip is 75 km per hour. His average velocity for the whole trip is zero.
Answer:
Explanation:
Given
Two block are connected by rope 
rope is attached to block 2
suppose
is a force applied to Rope
Applied force
=Tension in Rope 2

where a=acceleration of system
Tension in rope
is denoted by 

divide 1 and 2 we get

also 



Answer:
h = 2 R (1 +μ)
Explanation:
This exercise must be solved in parts, first let us know how fast you must reach the curl to stay in the
let's use the mechanical energy conservation agreement
starting point. Lower, just at the curl
Em₀ = K = ½ m v₁²
final point. Highest point of the curl
= U = m g y
Find the height y = 2R
Em₀ = Em_{f}
½ m v₁² = m g 2R
v₁ = √ 4 gR
Any speed greater than this the body remains in the loop.
In the second part we look for the speed that must have when arriving at the part with friction, we use Newton's second law
X axis
-fr = m a (1)
Y Axis
N - W = 0
N = mg
the friction force has the formula
fr = μ N
fr = μ m g
we substitute 1
- μ mg = m a
a = - μ g
having the acceleration, we can use the kinematic relations
v² = v₀² - 2 a x
v₀² = v² + 2 a x
the length of this zone is x = 2R
let's calculate
v₀ = √ (4 gR + 2 μ g 2R)
v₀ = √4gR( 1 + μ)
this is the speed so you must reach the area with fricticon
finally have the third part we use energy conservation
starting point. Highest on the ramp without rubbing
Em₀ = U = m g h
final point. Just before reaching the area with rubbing
= K = ½ m v₀²
Em₀ = Em_{f}
mgh = ½ m 4gR(1 + μ)
h = ½ 4R (1+ μ)
h = 2 R (1 +μ)
Answer:

Explanation:
Force on a current carrying rod due to magnetic field is given as

here we know that
current in the rod


now magnetic force is balanced by the weight of the rod
so we will have



A.
Gases do not have a definite volume.
Explanation:
This observation suggests that the gases do not have a definite volume. Gases moves randomly and will expand to take up the shape of containers they are introduced into.
- The particles of a gas are very far apart.
- They are held together by very weak attractive forces
- Gases are random and they frequently collide with one another and the walls of the containers they are put into.
- They have no fixed volumes
learn more:
Kinetic theory of matter brainly.com/question/12362857
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