<h2>
Answer:</h2>
Time
<h2>
Explanation:</h2>
The average speed of an object that is moving is defined as the distance traveled divided by the time of travel. You can measure the distance with a ruler and the time with a stopwatch. This can be expressed as the following formula:
For instance, if an object travels a distance 
in 4 seconds, the the average speed is:
By the law of universal gravitation, the gravitational force <em>F</em> between the satellite (mass <em>m</em>) and planet (mass <em>M</em>) is
<em>F</em> = <em>G</em> <em>M</em> <em>m</em> / <em>R </em>²
where
<em>• G</em> = 6.67 × 10⁻¹¹ m³/(kg•s²) is the universal gravitation constant
• <em>R</em> = 2500 km + 5000 km = 7500 km is the distance between the satellite and the center of the planet
Solve for <em>M</em> :
<em>M</em> = <em>F R</em> ² / (<em>G</em> <em>m</em>)
<em>M</em> = ((3 × 10⁴ N) (75 × 10⁵ m)²) / (<em>G</em> (6 × 10³ kg))
<em>M</em> ≈ 2.8 × 10¹⁴ kg
We use the following expression
T = 2*pi *sqrt(l/g)
Where T is the period of the pendulum
l is the length of the pendulum
and g the acceleration of gravity
We solve for l
l = [T/2*pi]² *g = [30s/2*pi]²* 9.8 [m/s²] = 223.413 m
The tower would need to be at least 223.413 m high
Answer:
Acceleration will be 
Explanation:
We have given initial speed of the car is 70 km/hr
We know that 1 km = 1000 m
And 1 hour = 3600 sec
So 
It is given that car stops in 12 sec
So final speed of the car v = 0 m/sec
Time t = 12 sec
From first equation of motion v = u+at
So 
( negative sign indicates that speed of the car will constantly decrease )
