Answer:
10880N
Explanation:
We are given that
Mass of elevator, m=850 kg
Acceleration, 

We have to find the tension in the cable.
We know that
When elevator is accelerating upward then tension in the cable

Using the formula


Answer:
Energy, 9 kWh or 32400 kJ
Explanation:
Given that,
The power of heater, P = 3 kW
It runs for 3 hours to raise the water temperature to the desired level. We need to find the amount of electric energy used. We know that the electrical power of an object is given by total energy delivered per unit time. It is given by :



E = 9 kWh
Since, 1 kWh = 3600 kJ
E = 32400 kJ
So, the amount of electric energy used is 9 kWh or 32400 kJ. Hence, this is the required solution.
Answer:
The speed of the object just before it hits Earth is 
(A) is correct option.
Explanation:
Given that,
M = mass of earth
R = radius of earth
The potential energy at height above the surface of the earth

The kinetic energy at height above the surface of the earth

The total energy at height above the surface of the earth

....(I)
The total energy at the surface of the earth
....(II)
We need to calculate the speed of the object just before it hits Earth
From equation (I) and (II)

Here, h = R


Hence, The speed of the object just before it hits Earth is
.
Since vectors are essentially quantities that have direction, D must be the answer as it contains a direction (down) while the other ones do not.