Answer:
Explanation:
Work is defined as the scalar product of force and distance
W=F•d
Given that
F = 8.5i + -8.5j. +×-=-
F=8.5i-8.5j
d = 2.5i + cj
If the work in the practice is zero, then W=0
therefore,
W=F•ds
0=F•ds
0=(8.5i -8.5j)•(2.5i + cj)
Note that
i.i=j.j=k.k=1
i.j=j.i=k.i=i.k=j.k=k.j=0
So applying this
0=(8.5i -8.5j)•(2.5i + cj)
0= (8.5×2.5i.i + 8.5×ci.j -8.5×2.5j.i-8.5×cj.j)
0=21.25-8.5c
Therefore,
8.5c=21.25
c=21.25/8.5
c=2.5
<span>What I have here is exactly the same problem, however, with the time changed to 19 mins:
metabolic energy = metabolic power*time = 1.150*19*60 = 1.311 kJ..corresponding to 1.311/4.186 = 313,2 Cal or kcal
If we reasonably assume a metabolic eff.cy of 20%, it means we need to assume food for 1500 Cal approx.
Just plug the value t=15min to the equation and you will surely get the correct answer.
I hope my answer has come to your help. Thank you for posting your question here in Brainly. We hope to answer more of your questions and inquiries soon. Have a nice day ahead!
</span>
Complete Question
The complete question is shown on the first uploaded image
Answer:
The velocity is 
in positive x -direction
The speed is 
Explanation:
From the question we are told that
The distance from the house to truck is D = 20 m
The distance traveled back to retrieve wind-blown hat is d = 15
The distance from the wind-blown hat position too the truck is k = 20 m
The total time taken is t = 75 s
Generally when calculating the displacement the Justin's backward movement to collect his wind - blown hat is taken as negative
Generally Justin's displacement is mathematically represented as
=> 
Generally the average velocity is mathematically represented as
=> 
=>
Generally the distance covered by Justin is mathematically represented as
=> 
=> 
Generally Justin's average speed over a 75 s period is mathematically represented as
=> 
=>
Answer:
The angular acceleration of CD player is 
.
Explanation:
Initial angular speed of a CD player is 0 and final angular speed is 41.8 rad/s. Time to change the angular speed is 3 s.
It is required to find the angular acceleration. The change in angular speed of the CD player divided by time taken is called its angular acceleration. It can be given by :
So, the angular acceleration of CD player is .
Answer:
The current in the second loop will stay constant
Explanation:
Since the induced emf in the second coil, ε due to the changing current i₁ in the first wire loop ε = -Mdi₁/dt where M = mutual inductance of the coils and di₁/dt = rate of change of current in the first coil = + 1 A/s (positive since it is clockwise)
Now ε = i₂R where i₂ = current in second wire loop and R = resistance of second wire loop.
So, i₂R = -Mdi₁/dt
i₂ = -Mdi₁/dt/R
Since di₁/dt = + 1 A/s,
i₂ = -Mdi₁/dt/R
i₂ = -M × + 1 A/s/R
i₂ = -M/R
Since M and R are constant, this implies that i₂ = constant
<u>So, the current in the second wire loop will stay constant.</u>
