a car accelerates from rest at 3 m / s^2 along a straight road. how far has the car travelled after 4 s
1 answer:
Answer:
24 m
Explanation:
The motion of the car is a uniformly accelerated motion (=at constant acceleration), therefore we can find the distance covered by using the following suvat equation:
where
s is the distance covered
u is the initial velocity
t is the time elapsed
a is the acceleration
For the car in this problem:
u = 0, since the car starts from rest
is the acceleration
t = 4 s is the time elapsed
Therefore, the distance covered is:
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Answer:
W = (F1 - mg sin θ) L, W = -μ mg cos θ L
Explanation:
Let's use Newton's second law to find the friction force. In these problems the x axis is taken parallel to the plane and the y axis perpendicular to the plane
Y Axis
N - =
N = W_{y}
X axis
F1 - fr - Wₓ = 0
fr = F1 - Wₓ
Let's use trigonometry to find the components of the weight
sin θ = Wₓ / W
cos θ = W_{y} / W
Wₓ = W sin θ
W_{y} = W cos θ
We substitute
fr = F1 - W sin θ
Work is defined by
W = F .dx
W = F dx cos θ
The friction force is parallel to the plane in the negative direction and the displacement is positive along the plane, so the Angle is 180º and the cos θ= -1
W = -fr x
W = (F1 - mg sin θ) L
Another way to calculate is
fr = μ N
fr = μ W cos θ
the work is
W = -μ mg cos θ L