Answer:
Wedge
Explanation:
Scissors are a pair of wedges that are combined together.
Answer:
We should not consider the needs of humans first because Conservation of nature is more important.
Explanation:
Human beings are important but the priority must be given to nature. Human beings have uncountable needs and if we focus on satisfying all such needs then it will affect our nature. Because finally our needs are fulfilled by using the resources from nature.
So rather than considering the needs of humans first, we must try to preserve our nature as much as possible. It is not done then it will lead to disaster.
Car X traveled 3d distance in t time. Car Y traveled 2d distance in t time. Therefore, the speed of car X, is 3d/t, the speed of car Y, is 2d/t. Since speed is the distance taken in a given time.
In figure-2, they are at the same place, we are asked to find car Y's position when car X is at line-A. We can calculate the time car X needs to travel to there. Let's say that car X reaches line-A in t' time.

Okay, it takes t time for car X to reach line-A. Let's see how far does car Y goes.

We found that car Y travels 2d distance. So, when car X reaches line-A, car Y is just a d distance behind car X.
Answer:
The question is incomplete. However, I believe, it is asking for the acceleration of the elevator. This is 3.16 m/s².
Explanation:
By Hooke's law, 
F is the force on a spring, k is the spring constant and e is the extension or compression.
From the question,

This is the force on the mass suspended on the spring. Its acceleration, a, is given by



This acceleration is more than the acceleration due to gravity, g = 9.8 m/s². Hence the elevator must be moving up with an acceleration of
12.96 - 9.8 m/s² = 3.16 m/s²
Answer:
Speed of the airplane 10.0 s later = 12.2 m/s
Explanation:
Mass of Boeing 777 aircraft = 300,000 kg
Braking force = 445,000 N
Deceleration

Initial velocity, u = 27 m/s
Time , t = 10 s
We have equation of motion, v =u +at
v = 27 + (-1.48) x 10 = 27 - 14.8 = 12.2 m/s
Speed of the airplane 10.0 s later = 12.2 m/s