Answer:
Explanation:
The oly way we can figure this out is if the boy is pulling the sled at a constant velocity. If not, we need a value for acceleration, and you don't have that here. If the boy is pulling the sled at a constant velocity, then the value for acceleration is 0, making this a really simple problem. I'm going with that, since there is no way to answer you otherwise. If velocity is not constant, please either repost the question or put it in the notes section under the question as it stands. If acceleration is 0, then
F - f = ma becomes
F - f = m(0) which is
F - f = 0 and
F = f which says that the applied force is the same as the frictional force. We need then to find the frictional force, which has an equation of
f = μ
where normal force is the same as the weight of the 2 girls. We will find that, then:
Each girl's mass is different so the normal force/weight equation is
w = (30.0)(9.8) + (40.0)(9.8) to get
w = 290 + 390 and
w = 680. Plug that into the frictional force equation:
f = (.120)(680) so
f = 82N
Bank turned help drivers maintain speed they keep the car from skidding
Answer:
No
Explanation:
According to physics, the work done by porter is zero but in reality porter gets tired as muscular energy is being used up.
In physics, work is the dot product of force and displacement. when the porter moves with the luggage, the weight act downwards while the porter moves forward. The angle between force and displacement is 90°. Thus, work done by the porter is zero.
The muscles are doing work in this case which is not calculated in physics.
Power is the rate of energy consumed during the work.
Answer:
Explanation:
a ) Let T be tension in the horizontal cable .
Taking torque about hinge of weight and tension
45000 x 7 x cos37 = 3.5 sin 37 x T
T = 119431 N
b ) If R be the reaction force on the hinge
R sin 37 = 45000 ( vertical force balancing each other )
R = 74775 N
c ) The direction of R will be along the bridge
d ) Moment of inertia of bridge
I = Ml² / 3 = (45000 / 9.8 ) x 14² / 3
= 300000.
When cable breaks , the weight creates a torque about the hinge will creates angular acceleration
Torque by weight about the hinge
= 45000 x 7 x cos 37
= 251570
angular acceleration = torque / moment of inertia
= 251570 / 300000
= .84 radian / s²
