Answer:
C) less than 129 lb.
Explanation:
Let the elevator be slowing up with magnitude of a . That means it is accelerating downwards with magnitude a .
If R be the reaction force
For the elevator is going downwards with acceleration a
mg - R = ma
R = mg - ma
R measures its apparent weight . Spring scale will measure his apparent weight.
So its apparent weight is less than 129 lb .
Answer:
Explanation:
Magnetic field due to a long wire
B = ( μ₀ / 4π ) x 2 I / r ( I is current through the wire )
= (μ₀ Q t ) / ( 2 π r ) [ I = Q t ]
b ) Magnetic field will change through the length of the square shaped loop . So we shall have to take the help of integration to calculate the flux through the loop.
Flux Φ = ∫ B dA
=∫ ( μ₀ / 4π ) x 2 I / r dA
10⁻⁷ x 2 I ∫ a dr/r
2 x 10⁻⁷ x Qt x a [ ln (2.9+1.2) / 1.2 ]
4.6 x 10⁻⁷ x 2.9 x 10⁻² t ln 4.1 / 1.2
16.4 x 10⁻⁹ t
Φ( t ) = 16.4 x 10⁻⁹ t
Induced emf = dΦ( t ) / dt = 16.4 x 10⁻⁹ v
current
16.4 x 10⁻⁹ / 2.5
= 6.56 x 10⁻⁹
Answer:
a) 
b) 
c) 
d) 
e) Since Dave starts from house and finally returns to the house so displacement is zero.
Explanation:
Given:
- distance between the house and the store,
- speed of driving from house to store,
- speed of driving back from store to house,
Since the store is located towards east from his house and the velocity in this direction is taken negative and contrary to this the velocity in the west direction is taken positive.
a)
time taken in reaching the store:
b)
Now the time taken in returning form the store:
therefore total time taken by the trip:
c)
the time taken by the trip in minutes:
d)
distance travelled in the whole trip:
e)
Since Dave starts from house and finally returns to the house so displacement is zero.
A person sitting in a chair not moving because a projectile is a moving object
B? I'm just guessing and I hope I'm right
