#14 isn't really a Physics problem. It's more of just reading a graph.
A). When speed changes, acceleration is
(change in speed) / (time for the change) .
To be correct about it, acceleration can be positive ... when speed
is increasing ... or it can be negative ... when speed is decreasing.
So, on this graph, there are two periods of acceleration:
From zero to 2 seconds, acceleration = (8 m/s) / (4 sec) = 2 m/s² .
From 10 to 12 seconds, acceleration = (-4 m/s) / (2 sec) = -2 m/s² .
B). From 12 to16 seconds, you can read the speed right from
the graph. It's 4 m/s .
C). From 2 to 10 seconds, the objects speed is a steady 8 m/s.
Covering 8 m/s every second for 8 seconds, it covers 64 meters.
Do you remember that distance is the area under the speed/time
graph? You can see that plainly on this graph. From 2 to 10 sec,
there are 16 blocks. Each block is (2 m/s) high and (2 sec) wide,
so its area is (2 m/s) x (2 sec) = 4 meters. The area of 16 blocks
is (16) x (4 meters) = 64 meters.
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#15.
a). constant velocity on a distance graph is a line that slopes up;
constant velocity on a velocity graph is a horizontal line;
b). positive constant acceleration on a distance graph is a
line that curves up;
positive constant acceleration on a velocity graph is a
straight line that slopes up;
c). "uniformly slowing down to a stop" on a distance graph
is a line that's less and less curved as time goes on, and
eventually reaches the x-axis.
"uniformly slowing down to a stop" on a velocity graph is
a straight line that slopes down, and stops when it reaches
the x-axis.
Solution: C. Pangea
The hypothesis of Continental drift suggests that in past, there was only one landmass on the Earth -Pangaea which drifted apart due to movement of plate tectonics causing earthquake. This hypothesis is supported by many evidences which includes presence of similar fossils on different landmasses, common land features such as widespread presence of glacial sediments etc.
-- sometimes presented as a "perpetual motion machine" /// -- impossible to construct /// -- a scam /// -- a fraud /// -- often lubricated with snake oil
Acceleration of the both masses tied together= 6m/s²
Explanation:
The force is given by F= ma
so 5= m1 (8)
m1=0.625 Kg
for m2
5=m2 (24)
m2=0.208 kg
now total mass= m1+m2=0.625+0.208
Total mass=M=0.833 Kg
now F= ma
5= 0.833 (a)
a= 5/0.833
a=6m/s²
