Answer:
(a) 
(b) 
(c) 
Explanation:
(a) According to Newton's second law, the acceleration of a body is directly proportional to the force exerted on it and inversely proportional to it's mass.

(b) According to Newton's third law, the force that the sled exerts on the girl is equal in magnitude but opposite in the direction of the force that the girl exerts on the sled:

(c) Using the kinematics equation:

For the girl, we have
and
. So:

For the sled, we have
. So:

When they meet, the final positions are the same. So, equaling (1) and (2) and solving for t:

Now, we solve (1) for 

F=ma
8480=26.5m
m=8480/26.5
m=320
The mass of the cart is 320kg.
Answer:
4.5 W
Explanation:
Applying,
P = V²/(R₁+R₂).................. Equation 1
Where P = Power, V = Voltage, R₁ and R₂ = values of the two resistor.
From the question,
Given: V = 9.00 V, R₁ = 7.00 Ω, R₂ = 11.00 Ω
Substitute these values into equation 1
P = 9²/(7+11)
P = 81/(18)
P = 4.5 Watt.
Hence the power dessipated by the two resistors is 4.5 watt
<h3>Answer</h3>
a. 8J
b. 90J
<h3>Notes formula</h3>
W = F × s
W = Work done (J)
F = Force (N)
s = distance (m)
<h3>Known that </h3>
a. F = 4N
s = 2m
b. F = 30N
s = 3m
<h3>Question</h3>
a. W = ..?
b. W = ..?
<h3>Way to do it</h3>
a. W = F × s
= 4N × 2m = 8J
b. W = F × s
= 30N × 3m = 90J
<em>#Moderators please don't be mean, dont delete my answers just to get approval from your senior or just to get the biggest moderation daily rank.</em>