Answer:
ΔK = 24 joules.
Explanation:
Δ
Work done on the object
Work is equal to the dot product of force supplied and the displacement of the object.
* Δ
Δ can be found by subtracting the vectors (7.0, -8.0) and (11.0, -5.0), which is written as Δ = (11.0 - 7.0, -5.0 - -8.0) which equals (4.0, 3.0).
This gives us
* 
= 
= 
J
Answer:
Displacement after 5 seconds is 155/2 meters
Explanation:
Let X (t) represent the equation of the position, then you have to d2x / dt2 = 5.
Applying the fundamental theorem of the calculation dx/dt = 5t + vo. The speed equation is V (t) = 5t + vo. Since the initial velocity is 30m/s, V (0) = 5 (0) + vo = 30. Therefore, V (t) = dx/dt = 5t + 30. Applying again the fundamental theorem of the calculation X (t) = 5t^2 / 2 + 30t + xo.
Displacement in 5 seconds is given by X (5) - X (0).
X (5) - X (0) = 5 (5)^2/2 +3 (5) + Xo - 5 (0)^2/2 -3 (0) -Xo = 155/2
Displacement after 5 seconds is 155/2 meters
Answer:
The amount of energy added to rise the temperature Q = 17413.76 KJ
Explanation:
Mass of water = 52 kg
Initial temperature 
= 68 °F = 20° c
Final temperature 
= 212 °F = 100° c
Specific heat of water 
Now heat transfer Q = m × C × ( - )
⇒ Q = 52 × 4.186 × ( 100 - 20 )
⇒ Q = 17413.76 KJ
This is the amount of energy added to rise the temperature.
Correct question is;
A ballet dancer spins with 2.4 rev/s with her arms outstretched,when the moment of inertia about axis of rotation is I. With her arms folded,the moment of inertia about the same axis becomes 0.6I about the same axis. Calculate the new rate of spin.
Answer:
4 rev/s
Explanation:
We are given;
Initial Angular velocity; ω_i = 2.4 rev/s
Initial moment of inertia; I_i = I
Final moment of inertia; I_f = 0.6I
From conservation of angular momentum, we have;
I_i × ω_i = I_f × ω_f
Where ω_f is the new rate of spin.
Thus, let's make it the subject to get;
ω_f = (I_i × ω_i/I_f)
Plugging in relevant values, we have;
ω_f = (I × 2.4/0.6I)
I will cancel out to give;
ω_f = 2.4/0.6
ω_f = 4 rev/s
In order to calculate the weight, we may simply use:
W = mg
W = 30 * 9.81
W = 294.3 N
The sum of the reaction force and the upward component of child pulling will be equal to total downward force. The force acting downwards is the weight. Therefore:
R + 12sin(45) = 294.3
R = 285.82 N
The acceleration can be found using the resultant force and the mass of the sled. The resultant force is:
F(r) = pulling force + pushing force - friction
F(r) = 12cos(45) + 8 - 5
F(r) = 11.48 N
a = F/m
a = 11.48 / 30
a = 0.38 m/s²
