The car undergoes an acceleration <em>a</em> such that
(45.0 km/h)² - 0² = 2 <em>a</em> (90 m)
90 m = 0.09 km, so
(45.0 km/h)² - 0² = 2 <em>a</em> (0.09 km)
Solve for <em>a</em> :
<em>a</em> = (45.0 km/h)² / (2 (0.09 km)) = 11,250 km/h²
Ignoring friction, the net force acting on the car points in the direction of its movement (it's also pulled down by gravity, but the ground pushes back up). Newton's second law then says that the net force <em>F</em> is equal to the mass <em>m</em> times the acceleration <em>a</em>, so that
<em>F</em> = (4500 kg) (11,250 km/h²)
Recall that Newtons (N) are measured as
1 N = 1 kg • m/s²
so we should convert everything accordingly:
11,250 km/h² = (11,250 km/h²) (1000 m/km) (1/3600 h/s)² ≈ 0.868 m/s²
Then the force is
<em>F</em> = (4500 kg) (0.868 m/s²) = 3906.25 N ≈ 3900 N
We are given with 98 Newton weight of an object on the surface of the earth with an acceleration equal to 9.8 m/s2. This means the mass of the object is equal to 98/9.8 or 10 kg. Hence the weight of the object 10,000 kilometers above sea level where acceleration is 1.49 m/s2 is 14.9 Newtons.
physical property is a characteristics of a pure substance that can be observed without changing the substance into someone else.
