Answer:
Making the lumber thick will make it stiff, which seems good. On the other hand, with thicker lumber, differences in expansion on the two faces have more leverage to make the lumber move.
Answer:

Explanation:
given,
weight of swimmer = 510 N
length of ledge, L = 1.75 m
vertical height of the cliff, h = 9 m
speed of the swimmer = ?
horizontal velocity of the swimmer should be that much it can cross the wedge.
distance = speed x time
d = v_x × t
1.75 = v_x × t ........(1)
now,time taken by the swimmer to cover 9 m
initial vertical velocity of the swimmer is zero.
using equation of motion for time calculation


t² = 1.938
t = 1.39 s
same time will be taken to cover horizontal distance.
now, from equation 1
1.75 = v_x × 1.39

horizontal speed of the swimmer is equal to 1.26 m/s
Answer:
A. The amount of mass changes only slightly during a chemical
reaction.
: You could make slight changes to the process or consider wheather the experiment was carried out correctly
F=W=mg
12N(given)= m*9.8
m= 1.22 kg