RED TEST
A sled is pulled up a hill in 10.5 s. If 425 J of work is done, what is the power used? A- 24.7 W B- 40.5 W C- 247 W D- 4,460 W
B- 40.5 W
which is something a machine can NOT do? A- decrease input force B- increase input force C- decrease input work D- increase input work
D- increase input work
which of the following is an inclined plain?
A- pulley
B- screw
C- wheel and axle
D- lever
B- screw
efficiency equation
eff=wout/win times 100%
how does an incline plain chage the force needed to lift an object?
reduce the force needed
What causes the efficiency of a machine to be less than 100%? A- friction B- gravity C- input force D- reaction force
A- friction
Which of the following is a requirement for work to be done?
A- Force is exerted
B- Object is carried
C- Force moves an object
D- Machine is used
C- force moves an object
for a given input force, a ramp increases wgich of the following?
A- height
B- output force
C- output work
D- effiency
B- output force
to do work how must a force make an object move?
you must applie force to an object and the force must move in the sane direction
How far did you push a box if you did 63 j of work and pushed with a force of 25 N? A- 0.4 m B- 1.6 m C- 2.5 m D- 13 m
C- 2.5 m
How much work is done when s force of 30 N moves an object a distance of 3 m?
A-3 J
B- 10 J
C- 30 J
D- 90 J
D- 90 J
work equation
w= fd
how are screws related to inclied plains?
the thread around it
You push a cart with a force of 12 N for a distance of 1.5 m. The cart rolls 1.1 m after you stop pushing. How much work is done? A- 8.0 J B- 13 J C- 18 J D- 31 J
C- 18 J
How much power is used when 600 J of work are done in 10 s?
A- 6 W
B- 60 W
C- 600 W
D- 610 W
B- 60 W
power equation
p=w/t
how does a fixed pulley afect the input force?
it canges the direction
How much energy is used by a 75-W light bulb in 5 s? A- 15 J B- 75 J C- 150 J D- 375 J
D- 375 J
What is the ideal mechancal advantage of a machine that changes only the direction of the input force?
A- less than 1
B- zero
C- 1
D- greater than 1
C- 1
machanical advatage equation
ma= fout/fin
when is the mechanical advantage less than 1?
when the input force is greater than the output