Answer:
The unknown force will be 18.116 lb.
Explanation:
Given that,
Three forces act on a flange as shown in figure.
The net force acting on the flange is a minimum.

We need to calculate the unknown force
Using formula of net force

Put the value into the formula


The magnitude of net force,




On differentiating w.r.to F




Negative sign shows the direction of force which is downward.
Hence, The unknown force will be 18.116 lb.
<span>This law means that when one object exerts force on another, the same amount of force is exerted on the initial object, but in the opposite reaction. For example, when a billiard ball strikes another ball, the second ball is propelled forward. Simultaneously, the momentum of the first ball is slowed or stopped by opposing force. The amount that the first object is affected by the opposing force depends on the mass and motion of the second object.</span>
Explanation :
It is given that, the driver accelerates from a stop sign, cruises for 20 s at a constant speed of 60 km/h, and then brakes to come to a stop 40 s after leaving the stop sign.
We know that acceleration is defined as the rate of change of velocity.

Where
dv is the change in velocity, dv = 0 - 60 m/s = -60 m/s
dt is the change in time, dt = 40 s - 30 s = 10 s
So, 

From the graph it is clear that, from 30 s to 40 s the car is decelerating. So, at every second within this time the value of acceleration will be same i.e.
.
When you talk about rate, you will expect that it will be in terms of a time unit. It measures how fast it is going. So, you would expect that the denominator is in time units. For the movement, you can measure this with either distance or velocity.
So, for the first variety, you would need distance and time to measure the rate of how far you go at a certain time. It is also called as velocity. For the second variety, you would need velocity and time to measure the rate of how fast you are going at a certain interval. It is also called as acceleration.
Answer:
A - elastic since many other fast food items could be considered close substitutes.
Explanation:
The price elasticity of demand is how much the demand of the Big Macs will change due to a 1% change in price. Should the elasticity be greater than 1, the Big Macs will be elastic. Should it be less than 1, the Big Macs are inelastic.
Demand elasticity is calculated as the percentage change in quantity demanded divided by a percentage change in price.
Since Big Macs are (i) a luxury good, and (ii) have close substitutes (other burgers available at McDonalds and other fast food stores), we will say their elasticity is greater than 1.
This means that the demand of Big Macs will change due to a 1% increase in price due to the presence of close substitutes.