Answer:
1.53m
Explanation:
Given parameters:
Mass of box = 3kg
Gravitational potential energy = 45J
Unknown
Height of the box = ?
Solution:
To solve this problem;
Gravitational potential energy = mgh
m is the mass
g is the acceleration due to gravity
h is the height
45 = 3 x 9.8 x h
h = 1.53m
This is a bit too broad. Maybe this is something to google up
Answer:
The power output of this engine is 
The the maximum (Carnot) efficiency is 
The actual efficiency of this engine is 
Explanation:
From the question we are told that
The temperature of the hot reservoir is 
The temperature of the cold reservoir is 
The energy absorbed from the hot reservoir is 
The energy exhausts into cold reservoir is 
The power output is mathematically represented as

Where t is the time taken which we will assume to be 1 hour = 3600 s
W is the workdone which is mathematically represented as

substituting values

So


The Carnot efficiency is mathematically represented as



The actual efficiency is mathematically represented as

substituting values


Momentum, p = m.v
m of the girl = 60.0 kg
m of the boat = 180 kg
v of the girl = 4.0 m/s
A) Momentum of the girl as she is diving:
p = m.v = 60.0 kg * 4.0 m/s = 24.0 N/s
B) momentum of the raft = - momentum of the girl = -24.0 N/s
C) speed of the raft
p = m.v ; v = p/m = 24.0N/s / 180 kg = -0.13 m/s [i.e. in the opposite direction of the girl's velocity]