Complete Question
The complete question is shown on the first and second uploaded image
Answer:
The minimum mass of
correct option is E
Explanation:
Free body diagram of the set up in the question is shown on the third uploaded image
The mass of board is 
The length of the board is 
The length extending over the edge is 
The second mass is 
Now to obtain
we take moment about the edge of the platform

Substituting value


Answer:
v = 2 m/s
Explanation:
The object moves 20 m in 10 s initially. Then it remains at rest for 20 s. It is required to find the average speed of the object.
Fro 10 s it covers 20 m. For that time, speed is :

For 20 s, it was at rest means distance covered is 0. So, speed is 0.
The average speed of the object is equal to the sum of speed for 10 s and for 20 s i.e.
v = 2 m/s + 0 = 2 m/s
So, the average speed of the object is 2 m/s.
A. Acceleration is the answer to you question. When an object changes velocity it can accelerate.<span />
Answer:
The position of the person's feet. a running shoe company studying how different surfaces affect the life of a shoe tread
Explanation:
100%
It is used to classify the climates around the world