Answer:
Approximately 
, assuming that 
.
Explanation:
Let 
and 
denote the mass and acceleration of Spiderman, respectively.
There are two forces on Spiderman:
- Downward gravitational attraction from the earth:
. - Upward tension force from the strand of web
.
The directions of these two forces are exactly opposite of one another. Besides, because Spiderman is accelerating upwards, the magnitude of (which points upwards) should be greater than that of 
(which points downwards towards the ground.)
Subtract the smaller force from the larger one to find the net force on Spiderman:
.
On the other hand, apply Newton's Second Law of motion to find the value of the net force on Spiderman:
.
Combine these two equations to get:
.
Therefore:
.
By Newton's Third Law of motion, Spiderman would exert a force of the same size on the strand of web. Hence, the size of the force in the strand of the web should be approximately 
(downwards.)
Answer:
a) t1 = v0/a0
b) t2 = v0/a0
c) v0^2/a0
Explanation:
A)
How much time does it take for the car to come to a full stop? Express your answer in terms of v0 and a0
Vf = 0
Vf = v0 - a0*t
0 = v0 - a0*t
a0*t = v0
t1 = v0/a0
B)
How much time does it take for the car to accelerate from the full stop to its original cruising speed? Express your answer in terms of v0 and a0.
at this point
U = 0
v0 = u + a0*t
v0 = 0 + a0*t
v0 = a0*t
t2 = v0/a0
C)
The train does not stop at the stoplight. How far behind the train is the car when the car reaches its original speed v0 again? Express the separation distance in terms of v0 and a0 . Your answer should be positive.
t1 = t2 = t
Distance covered by the train = v0 (2t) = 2v0t
and we know t = v0/a0
so distanced covered = 2v0 (v0/a0) = (2v0^2)/a0
now distance covered by car before coming to full stop
Vf2 = v0^2- 2a0s1
2a0s1 = v0^2
s1 = v0^2 / 2a0
After the full stop;
V0^2 = 2a0s2
s2 = v0^2/2a0
Snet = 2v0^2 /2a0 = v0^2/a0
Now the separation between train and car
= (2v0^2)/a0 - v0^2/a0
= v0^2/a0
The gravitational force is inversely proportional to the
square of the distance between their centers. So the
force is greatest when the distance is zero.
