Mechanics | Relativity Answers

In an experiment involving the spiral spring, F is the restoring force and x the extension of the spring. The equation F = - kx gives the relationship between F and x. What does k measure in the experiment?

The Body Mass Index (BMI) is given by [BMI = mass / (height 2] where the mass is
measured in kg and height is measured in m. If a man of weight 800 N, and height 71 inches,
what is his BMI (in kg/m2)? Given that 1 m = 3.3 feet, and 1 foot =12 inches.

a) 11.3
b) 25.5
c) 28.2
d) 27.7
e) 23

An object of mass 10 kg is pulled across a rough floor at a constant speed of 4 m/s using a force of
40 N, then the coefficient of kinetic friction is (ignoring air resistance):
a) 0.4 b) 4 c) Zero d) 0.25 e) 2.5

A 4 kg mass is moving in a circular path of radius 2.5 m with a constant speed of 5 m/sec.
The centripetal force on the mass is
a ) 20 N. b ) 25 N. c ) 40 N. d ) 45 N. e ) 35 N.

A 23 kg boy sits 1.5 m from the axis of rotation of a seesaw. At what distance from the
axis of rotation must a 21 kg boy be positioned on the other side of the axis to balance the
seesaw?
a) 4.6 m
b) 2.6 m
c) 3.6 m
d) 1.6 m
e) 0.6 m

A typical laboratory centrifuge rotates at 4000 rev/min. What is the centripetal acceleration
at a point located 10 cm from the axis of rotation of the centrifuge?
a) 4.2×102 m/s2
b) 1.8×103 m/s2
c) 1.8×102 m/s2
d) 1.8×104 m/s2
e) 1.6×105 m/s2

Object A has mass of 2 kg and object B has mass of 4 kg. Both masses are dropped from the same
height. Upon reaching the ground, (Ignoring air resistance)
a) Object A has twice the speed of object B
b) Object B has twice the speed of object A
c) Object A has four times the speed of object B
d) Object A has same speed as object B
e) Object B has four times the speed of object A

If the coefficient of static friction between a patient and the bed sheets is 1.2, what is the
maximum angle (θ) at which the bed can be tilted with respect to the floor before the patient
begins to slide?

a) 45o
b) 60 o
c) 30 o
d) 50 o
e) 25 o

file:///Users/123456/Desktop/Document8.htm

Vector a has components ax = 15 and ay = 9 What is the approximate magnitude of the
vector ?
a) 17.5 b) 24 c) 10.9 d) 6.87 e) 12

A motorist travels 320 km at a speed of 80 km/h. It then traveled 320 km at a speed of 100
km/h along the same direction. What is the average speed of the motorist for the entire trip?
a) 84 km/h b) 90 km/h c) 89 km/h d) 91 km/h e) 95 km/h