Answer:
171.5 N
Explanation:
The gravitational force on an object due to the Earth is given by

where
m is the mass of the object
g is the acceleration due to gravity
The acceleration due to gravity at a certain height h above the Earth is given by

where:
G is the gravitational constant
is the Earth's mass
is the Earth's radius
Here,

So the acceleration due to gravity is

We know that the mass of the object is
m = 70 kg
So, the gravitational force on it is

A) 4.7 cm
The formula for the angular spread of the nth-maximum from the central bright fringe for a diffraction from two slits is

where
n is the order of the maximum
is the wavelength
is the distance between the slits
In this problem,
n = 5


So we find

And given the distance of the screen from the slits,

The distance of the 5th bright fringe from the central bright fringe will be given by

B) 8.1 cm
The formula to find the nth-minimum (dark fringe) in a diffraction pattern from double slit is a bit differente from the previous one:

To find the angle corresponding to the 8th dark fringe, we substitute n=8:

And the distance of the 8th dark fringe from the central bright fringe will be given by

A horizontal line on a speed/time graph means a constant speed.
The magnetic field direction and direction of induced current in a wire are related by the right hand grip rule. Since the magnetic field was upwards, the thumb points upwards and the fingers curl around it. When viewed from above, it is seen as a current flowing in the counter clockwise direction.
Answer : Total energy dissipated is 10 J
Explanation :
It is given that,
Time. t = 10 s
Resistance of the resistors, R = 4-ohm
Current, I = 0.5 A
Power used is given by :

Where
E is the energy dissipated.
So, E = P t.............(1)
Since, 
So equation (1) becomes :



So, the correct option is (3)
Hence, this is the required solution.