[صمت الفجر]

A boy holds a 40-N weight at arm’s length for 10 s. His arm is 1.5m above the ground. The
work done by the force of the boy on the weight while he is holding it is:
A. 0
B. 6.1J
C. 40 J
D. 60 J
E. 90 J

مني فاهمه السؤال
A horizontal force of 5.0N pushes a 0.50-kg book against a vertical wall. The book is initially
at rest. If the coefficients of friction are μs = 0.6 and μk = 0.80, the magnitude of the frictional
force is:
A. 0
B. 4.9N
C. 3.0N
D. 5.0N
E. 4.0N
مني فاهمه هو هنا اي احتكاك يبغى السكوني ولا الحركي ؟...



A horizontal force of 12N pushes a 0.50-kg book against a vertical wall. The book is initially
at rest. If μs = 0.6 and μk = 0.80, the acceleration of the book in m/s2 is:
A. 0
B. 9.4m/s2
C. 9.8m/s2
D. 14.4m/s2
E. 19.2m/s2

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A box rests on a rough board 10 meters long. When one end of the board is slowly raised to a
height of 6 meters above the other end, the box begins to slide. The coefficient of static friction
is:
A. 0.8
B. 0.25
C. 0.4
D. 0.6
E. 0.75

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A crate is sliding down an incline that is 35◦ above the horizontal. If the coefficient of kinetic
friction is 0.40, the acceleration of the crate is:
A. 0
B. 2.4m/s2
C. 5.8m/s2
D. 8.8m/s2
E. 10.3m/s2

A 5.0-kg crate is on an incline that makes an angle of 30◦ with the horizontal. If the coefficient
of static friction is 0.5, the maximum force that can be applied parallel to the plane without
moving the crate is:
A. 0
B. 3.3N
C. 30N
D. 46N
E. 55N

هنا زي هذا السؤال لمن طلب منيمم عرفت احلها وماكسمم يعني كيف احلها ؟؟يعني هو لم يطلب منيمم وماكسمم ايش يعيني يبغى بالزبط؟؟
...................
An object moving in a circle at constant speed:
A. must have only one force acting on it
B. is not accelerating
C. is held to its path by centrifugal force
D. has an acceleration of constant magnitude
E. has an acceleration that is tangent to the circle
................

A 0.2-kg stone is attached to a string and swung in a circle of radius 0.6m on a horizontal
and frictionless surface. If the stone makes 150 revolutions per minute, the tension force of the
string on the stone is:
A. 0.03N
B. 0.2N
C. 0.9N
D. 1.96N
E. 30N
150 revolutions per minute<<هذه ايش يعني ايش نستفيد منها ؟؟

...............

An object moves around a circle. If the radius is doubled keeping the speed the same then the
magnitude of the centripetal force must be:
A. twice as great
B. half as great
C. four times as great
D. one-fourth as great
E. the same


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