ito na ung hinihingi po ninyo sa physics. sensya na talga hindi ko masagutan ng maayos ung tanong . kaya yan lang sagot ko. kopyahin niyo kung gusto nyo. hindi ko sinisiguradong tama mga sagot ko ah.

1. (Work and Energy)

2. I.
Pablito Vibal is cutting grass again. The force he applies to the
lawnmower handle performs two functions. It helps to hold the wheel
down on the ground so they don’t slip, and it pushes the lawnmower
forward at a constatn velocity. Pablito is pushing with a force of 250
N at an angle of 38 degree to the (horizontal) ground. The lawnmower
weighs 100 N. Paul pushes a distance of 8m before stopping to wipe
his brow.
a) What is the horizontal component of the force applied by Pablito?
Ans:
b) How much work does Pablito do before wiping his brow?
Given: 250N = force
8m = distance
Formula:
W = (F)(d)
Solution:
W =(F)(d)
=(250N)(8m)
Or

3. II. A circus acrobat climbs onto her brother’s shoulders while he, in turn,
is standing on her father’s shoulders. They practice the feat while her
father is standing on the ground, although the whole thing is to be
done on the back of a galloping horse in an actual performance. The
female acrobat has a mass of 50kg and must climb a height of 3.0m
while the horse gallops (sideways) a distance of 7.0m around ring.
a) How much does the female acrobat weigh?
Ans:
b) How much work must she do ins practice while her father is
standing stationary on the ground?
Given:
50 kg = Mass
Cos 23 degree = (considered as distance)
Formula:
F = (m) ( )
Solution:
F = (m) ( )
F = (50kg)(cos 23 degree)
F=
c) How much work must she do in actual performance while the horse
is carrying her(and everyone else) sideways?

4. Given:
43.5N = force
7m = distance
Formula:
W = (F)(d)
Solution:
W = (43.5N)(7m)
= or
III.
Much of the time and expense in drilling an oil well goes into
changing the drill bit as it wears out. The drilling pipe must be
pulled up and disassembled one section at a time in order to pull
the drill bit out of the hole and replace it. A pipe 0.65 mile long
weighs 2400 lb . It takes the pulling works 7.5 s to lift this pipe
20ft, the height of one section, in order to disassemble it.
(One horsepower equals 550 ft-lb/s)
a) Howmuch work is done in lifting the pipe the length of one
section?
Given:
Formula:
Solution:

5. b) What is the power delivered by pulling in horsepower?
Given:
Formula :
Solution:
IV. An escalator in department store is driven by a large electric motor
whose power consumption changes with the load to keep the escalator
moving at a constant velocity, up to certain maximum power capacity.
An escalator working at 0.22 of its maximum power capacity lifts 18
people per minute a vertical height of 6.8m. these people have an
average mass of 73 kg.
a) How much work is done in 80s?
Given:
0.22hp = power
60s = time
Formula:
We use ratio & proportion to get the power (in 80sec = X)
(0.22hp) X
_______ = ______
60 sec 80sec

6. Solution :
(0.22hp) X
_______ = ______
60 sec 80sec
60X = 17.6
= 0.29hp
Now we have:
0.29hp as our power when 80 sec is done.
To get the work, we’ll use another formula.
(1hp = 550 ft-lb/s )
W = (P)(t)
=

7. b) What is the power delivered by the escalator in watts?
If:
1 watt = 1J/s or 1Nm/s
c) What is the maximum mass of people can the escalator deliver in
80s while working at its maximum power capacity?
Ans:
V. Annete Raymundo is measuring her acceleration on her ten-speed
bicycle. Annette produces an average power output of 0.10 hp for 20s
(1hp = 550 ft-lb/s). Almost all the kinetic energy goes into her bicycle
which has a combined weight of 588N.
a) How many joules of kinetic energy does she produce?
Given :
0.10 hp = power
20 s = time
Formula :
∆W = (Pave )(∆t)
Solution :