<span>If the refrigerator weights 1365 and you are not exerting any vertical force on it, then the normal force is also 1365N. so Fn=1365
Fsf = Static frictional force = (coefficient of static friction) * (Normal force)
So the least for you could exert to move it is equal to the Fsf.
Fsf = (0.49)(1365N)</span><span>
</span>
Answer:
16. 68.18 Km/h
17. 3 miles.
Explanation:
16. Determination of the speed
Distance travelled = 150 Km
Time = 2.2 hours
Speed =?
Speed is simply defined as the distance travelled with time. Mathematically, it is expressed as:
Speed = Distance / time
With the above formula, we can obtain the speed as follow:
Distance travelled = 150 Km
Time = 2.2 hours
Speed =?
Speed = Distance /time
Speed = 150 / 2.2
Speed = 68.18 Km/h
17. Determination of the distance.
Speed = 3 mph
Time = 1 hour
Distance =?
Speed = Distance /time
3 = distance / 1
Distance = 3 miles
I think metal, steel and copper.
Let's break the question into two parts:
1) The force needed in Ramp scenario.
2) The effort force needed in the lever scenario.
1. Ramp Scenario: In an incline, the only component of cart's weight(
mg) that is in the direction of motion is
. Therefore the effort force in this case must be equal or greater than
.
Now we need to find

.

is the angle between the incline of the ramp and the ground.
Since the height is
5m and the length of the ramp is
8m, 
would be
5/8 or 0.625. Now that you have

, mutiple it with
mg.
=> m*g*

= 20 * 10 * 5 / 8. (Taking g = 10 m/s² for simplicity) = 125N
Therefore, the minimum Effort force you would require in this case is
125N.
2. Lever Scenario:
Just apply "moment action" in this case, which is:


= ?

= mg = 20 * 10 = 200N

= 10m

= 1m
Plug-in the values in the above equation:

= 200/10=
20NAs 20N << 125N, the best choice is to use lever.