A 4.0-kg object has 72 J of kinetic energy. Determine its speed.
1 answer:
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Answer:
t ’= , v_r = 1 m/s t ’= 547.19 s
Explanation:
This is a relative velocity exercise in a dimesion, since the river and the boat are going in the same direction.
By the time the boat goes up the river
v_b - v_r = d / t
By the time the boat goes down the river
v_b + v_r = d '/ t'
let's subtract the equations
2 v_r = d ’/ t’ - d / t
d ’/ t’ = 2v_r + d / t
In the exercise they tell us
d = 1.22 +1.45 = 2.67 km= 2.67 10³ m
d ’= 1.45 km= 1.45 1.³ m
at time t = 69.1 min (60 s / 1min) = 4146 s
the speed of river is v_r
t ’=
t ’=
In order to complete the calculation, we must assume a river speed
v_r = 1 m / s
let's calculate
t ’=
t ’= 547.19 s
Answer : The time required is, 16.1 minutes.
Explanation :
First we have to calculate the amount of heat required to increase the temperature is:
where,
Q = amount of heat required = ?
m = mass
= density of air =
V = volume of air
C = specific heat of air =
= change in temperature =
Now put all the given values in above formula, we get:
Now we have to calculate the time required.
Formula used :
where,
t = time required = ?
Q = amount of heat required =
P = power = 1500 W
Now put all the given values in above formula, we get:
Thus, the time required is, 16.1 minutes.