D if the blue car started higher it would have more energy but since the red car is lower it is going faster because it’s going down a hill
The net force on the box is:
50 + 30 - 65
= 15 Newtons
This can be used in conjunction with
F = ma
to calculate the acceleration of the box if its mass is known.
Answer:
Explanation:
Given:
Acceleration, a = -2.4 m/s^2
Acceleration due to gravity, g = 9.8 m/s^2
Sum of forces = 0
Fr + F = 0
Fr = µsl × m × g
Since, Fn = m × g
m × a = (- µsl × mg)
µsl = -a/g
= 2.4/9.8
= 0.245
Take the object's starting direction of motion to be the positive direction, so that a stopping force acts in the opposite direction. By Newton's second law, the object undergoes an acceleration <em>a</em> such that
-15 N = (20 kg) <em>a</em>
Solve for <em>a</em> :
<em>a</em> = - (15 N) / (20 kg) = -0.75 m/s²
The object's velocity <em>v</em> at time <em>t</em> is then given by
<em>v</em> = 3 m/s + (-0.75 m/s²) <em>t</em>
so the time it takes for the object to slow to a rest is
0 = 3 m/s + (-0.75 m/s²) <em>t</em>
<em>t</em> = (3 m/s) / (0.75 m/s²) = 4.0 s
