Answer:
The additional trials needed is 48 trials
Explanation:
Given;
initial number of trials, n = 16 trials
the standard deviation, σ = 0.24 s
initial standard error, ε = 0.06 s
The standard error is given by;

To reduce the standard error to 0.03 s, let the additional number of trials = x

Therefore, the additional trials needed is 48 trials.
The work done by tension force of 14N applied on the laptop by a rope as it moves 2.0 mm up the slope is 0.028 J
W = F d cos θ
W = Work done
F = Force
d = Displacement
θ = Angle between force and displacement vector
F = 14 N
d = 2 mm = 0.002 m
θ = 0
W = 14 * 0.002 * 1
W = 0.028 J
Work done is the change in energy of an object. So if an object moves a certain distance, work is done on the object. If the force and displacement are perpendicular to each other there is no work done on the object.
Therefore, the work done by tension on the laptop is 0.028 J
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2. The zeros in front do not matter
Answer:
option E
Explanation:
given,
diameter = 4 mm
shutter speed = 1/1000 s
diameter of aperture = ?
shutter speed = 1/250 s
exposure time to the shutter time

N is the diameter of the aperture and t is the time of exposure
now,


inserting all the values

N₂² = 4
N₂ = 2 mm
hence , the correct answer is option E