By looking at the acceleration of the object.
In fact, Netwon's second law states that the resultant of the forces acting on an object is equal to the product between the mass m of the object and its acceleration:
So, when static friction is acting on the object, if the object is still not moving we know that all the forces are balanced: in fact, since the object is stationary, its acceleration is zero, and so the resultant of the forces (left term in the formula) must be zero as well (i.e. the forces are balanced).
When using a simple machine, the benefit of using less force to lift an object is offset by the need to push for a larger distance so that energy can be conserved.
<u>Explanation:
</u>
A simple machine utilized for completing the works easily. So in order for easy and quick completion of works, these machines may increase the amount of force acting on the object by increasing the velocity or speed of the machine. As velocity term is present so the machines may also change the directions of force acting on the object of concern to do the work soon just like pulley.
Also other way of completing the work with less input force requirement is by increasing the distance or area of action for the force acting on it. As work done is a measure of acting force on a region multiplied with the displacement occurred with that force.
It can be known that force seems to be inversely proportional to distance or area of action. So if we need to use less force to lift an object, it is offset by the need to push for a larger distance in order to conserve the energy.
Answer:
a) 0.64 b) 2.17m/s^2 c) 8.668joules
Explanation:
The block was on the ramp, the ramp was inclined at 20degree. A force of 5N was acting horizontal to the but not parallel to the ramp,
Frictional force = horizontal component of the weight of the block along the ramp + the applied force since the block was just about move
Frictional force = mgsin20o + 5N = 6.71+5N = 11.71
The force of normal = the vertical component of the weight of the block =mgcos20o = 18.44
Coefficient of static friction = 11.71/18.44= 0.64
Remember that g = acceleration due to gravity (9.81m/s^2) and m = mass (2kg)
b) coefficient of kinetic friction = frictional force/ normal force
Fr = 0.4* mgcos 20o = 7.375N
F due to motion = ma = total force - frictional force
Ma = 11.71 - 7.375 = 4.335
a= 4.335/2(mass of the block) = 2.17m/s^2
C) work done = net force *distance = 4.335*2= 8.67Joules
Avogadro's number is equal to 6.02 E 23
Thie means we have 6.02 E 23 marshmallows.
Assuming each marshmallow to be a small cylinder we can calculate the area of its base
Area circumference = pi*r² = pi * (0.635/2)² = 0.317 cm²
So, 6.02 E 23 marshmallows * 0.317 cm² cover a total area of
Area covered = 1.908 E 23 cm² = 1.908 E 13 km²
<span>The land area of california is 1.560 E 5 mi</span>² = 4.04 E 5 km²
If we divide the Areas >>>>
1.908 E 13 km² / 4.04 E 5 km² = 47. 227 E 6 (This is the number of times the area of California could be filled with those marshmallows)
Now for the height, we multiply this number times the height of each marshmallow
47. 227 E 6 * 2.54 cm = 119.96 E 6 cm = 1199.6 km above the surface
Answer:
7 s / 3600 s/hr = 0.001944444444... = 0.0019 hr
a = (vf - vi) / t = (70 - 0) / 0.0019 = 36000 km/hr²
