True or False An object will slow down and stop as long as no forces act upon it
2 answers:
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Answer:
a) a = 6.1 m/s^2
b) a = 0.98m/s^2
Explanation:
Mass of slab = 40kg
Mass of block = 10kg
Coefficient of static friction (Us) = 0.60
Kinetic coefficient (UK) = 0.40
Horizontal force = 100N
The normal reaction from 40kg slab on 10 kg block = 10*9.81
= 98.1N
Static frictional force = Us*R
= 98.1*0.6
= 58.86N
This is less than the force applied
If 10 kg block will slide on the 40 kg slab, net force = 100 - kinetic force
Kinetic force (Uk*R) = 0.4*98.1
= 39.28N
= 39N
Net force = 100 -39
= 61N
Recall that F = ma
For 10 kg block
a = F/m
a = 61/10
a = 6.1m/s^2
b) Frictional force on 40 kg slab by 10 kg = 98.1*0.4
= 39.24
= 39N
F = ma
a = F/m
For 40kg slab
a = 39/40
a = 0.98m/s^2
Answer:
Explanation:
For image formation in objective lens
object distance u = 14 +1 = 15 mm
focal length f = 14 mm .
image distance v = ?
lens formula
Putting the values
v = 210 mm .
B )
magnification = v / u
= 210 / 15
= 14
size of image = 14 x 1.1 mm
= 15.4 mm
= 15 mm approx
C )
For final image to be at infinity , image produced by objective lens must fall at the focal point of eye piece . so objective lens's distance from the image formed by objective must be equal to focal length of eye piece that is 21 mm .
21 mm is the answer .
D )
overall magnification =
D = 25 cm , f_e = focal length of eye piece
= 14 x 250 / 21
= 166.67
= 170 ( in two significant figures )