Answer:
Explanation:
mass of backpack, m = 8.1 kg
weight of climber, W = 656 N
height raised, h = 9.4 m
time, t = 28.2 min = 28.2 x 60 = 1692 second
weight of backpack, w = m x g = 8.1 x 9.8 = 79.38 N
Work done by the climber on the backpack = mg x h = 79.38 x 9.4 = 746.17 J
Wok done in lifting herself + backpack = (W + w) x h
= (656 + 79.38) x 9.4 = 6912.57 J
Power developed by the climber,P = Total work / time
P = 6912.57 / 1692 = 4.09 W
It is the thermal energy transferred from a hot object to a cool object.
The following statement listed above is correct.
Answer: True.
#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.
====================================
#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.
Answer:
0.95 seconds
Explanation:
t = Time taken
u = Initial velocity = 15 m/s
v = Final velocity
s = Displacement
a = Acceleration = 9.81 m/s² (downward positive, upward negative)
Time taken by the ball to reach the maximum height
Maximum height
Distance between maximum height of the ball and the branch is 11.47-7 = 4.46 m
So, the distance that will be covered on the way down is 4.46 m
Now
u = 0
s = 4.46
Time taken by the ball from the maximum height to the tree branch is 0.95 seconds.
Total time taken from the moment the ball is thrown to reach the tree branch is 1.52+0.95 = 2.47 seconds
<span>Cell membranes are selectively permeable because it allows some things to enter or leave the cell while keeping other things outside or inside the cell.</span>
