When a person ice skates, the surface of the ice actually melts beneath the blades, so that he or she skates on a thin sheet of water between the blade and the ice. (a) Find an expression for total friction force on the bottom of the blade as a function of skater velocity V, blade length L, water thickness (between the blade and the ice) h, water viscosity μ , and blade width W. (b) Suppose an ice skater of total mass m is skating along at a constant speed of V 0 when she suddenly stands stiff with her skates pointed directly forward, allowing herself to coast to a stop. Neglecting friction due to air resistance, how far will she travel before she comes to a stop? (Remember, she is coasting on two skate blades.) Give your answer for the total distance traveled, x, as a function of V 0 , m, L, h , μ , and W. (c) Find x for the case where V 0 = 4.0 m/s, m = 100 kg, L = 30 cm, W = 5.0 mm, and h = 0.10 mm. Do you think our assumption of negligible air resistance is a good one?
When a person ice skates, the surface of the ice actually melts beneath the blades, so that he or she skates on a thin sheet of water between the blade and the ice. (a) Find an expression for total friction force on the bottom of the blade as a function of skater velocity V, blade length L, water thickness (between the blade and the ice) h, water viscosity μ , and blade width W. (b) Suppose an ice skater of total mass m is skating along at a constant speed of V 0 when she suddenly stands stiff with her skates pointed directly forward, allowing herself to coast to a stop. Neglecting friction due to air resistance, how far will she travel before she comes to a stop? (Remember, she is coasting on two skate blades.) Give your answer for the total distance traveled, x, as a function of V 0 , m, L, h , μ , and W. (c) Find x for the case where V 0 = 4.0 m/s, m = 100 kg, L = 30 cm, W = 5.0 mm, and h = 0.10 mm. Do you think our assumption of negligible air resistance is a good one?
When a person ice skates, the surface of the ice actually melts beneath the blades, so that he or she skates on a thin sheet of water between the blade and the ice.
(a) Find an expression for total friction force on the bottom of the blade as a function of skater velocity V, blade length L, water thickness (between the blade and the ice) h, water viscosity
μ
, and blade width W.
(b) Suppose an ice skater of total mass m is skating along at a constant speed of V0when she suddenly stands stiff with her skates pointed directly forward, allowing herself to coast to a stop. Neglecting friction due to air resistance, how far will she travel before she comes to a stop? (Remember, she is coasting on two skate blades.) Give your answer for the total distance traveled, x, as a function of V0, m, L, h,
μ
, and W.
(c) Find x for the case where V0= 4.0 m/s, m = 100 kg, L = 30 cm, W = 5.0 mm, and h = 0.10 mm. Do you think our assumption of negligible air resistance is a good one?
500
Q3: The attachment shown in Fig.3 is made of
1040 HR. The static force is 30 kN. Specify the
weldment (give the pattern, electrode
number, type of weld, length of weld, and leg
size).
Fig. 3
All dimension
in mm
30 kN
100
(10 Marks)
(read image) (answer given)
A cylinder and a disk are used as pulleys, as shown in the figure. Using the data
given in the figure, if a body of mass m = 3 kg is released from rest after falling a
height h 1.5 m, find:
a) The velocity of the body.
b) The angular velocity of the disk.
c) The number of revolutions the cylinder has made.
T₁
F
Rd =
0.2 m
md =
2 kg
T
T₂1
Rc = 0.4 m
mc = 5 kg
☐ m = 3 kg
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