Answer:
Efficiency = 10.2 %
Explanation:
Given the following data;
Mass = 70 kg
Height = 50 m
Velocity = 10 m/s
We know that acceleration due to gravity is equal to 9.8 m/s².
To find the efficiency of energy conversion from potential to kinetic;
First of all, we would determine the potential energy;
P.E = mgh
P.E = 70 * 9.8 * 50
P.E = 34300 J
For the kinetic energy;
K.E = ½mv²
K.E = ½ * 70 * 10²
K.E = 35 * 100
K.E = 3500
Therefore, Input energy, I = 34300 J
Output energy, O = 3500 J
Next, we find the efficiency;
Efficiency = O/I * 100
Substituting into the formula, we have;
Efficiency = 3500/34300 * 100
Efficiency = 0.1020 * 100
Efficiency = 10.2 %
Answer:

Explanation:
Given,
The angle of the slide=
The mass of the child is= m
coefficient of friction = 0.20
when she slides down now apply Newton's law


therefore the acceleration

![a=g[\sin \theta -\mu \cos \theta]](https://tex.z-dn.net/?f=a%3Dg%5B%5Csin%20%5Ctheta%20-%5Cmu%20%5Ccos%20%5Ctheta%5D)
![a=9.8\times [\sin 42^\circ -0.2\times \cos 42^\circ]](https://tex.z-dn.net/?f=a%3D9.8%5Ctimes%20%5B%5Csin%2042%5E%5Ccirc%20-0.2%5Ctimes%20%5Ccos%2042%5E%5Ccirc%5D)

hence, the magnitude of acceleration during her sliding is equal to 
Answer:
i think the answer is B but im not sure
Answer:
F'= 4F/9
Explanation:
Two small objects each with a net charge of +Q exert a force of magnitude F on each other. If r is the distance between them, then the force is given by :
...(1)
Now, if one of the objects with another whose net charge is + 4Q is replaced and also the distance between +Q and +4Q charges is increased 3 times as far apart as they were. New force is given by :
.....(2)
Dividing equation (1) and (2), we get :

Hence, the correct option is (d) i.e. " 4F/9"
Answer:
- 1100 J heat flows out
Explanation:
dW = - 1600 J (as work is done on the gas)
dU = 500 J
dQ = ?
According to the first law of thermodynamics
dQ = dU + dW
dQ = 500 - 1600
dQ = - 1100 J
As heat is negative so it flows out.