Answer:the car was traveling at a speed of 80 ft/s when the brakes were first applied.
Step-by-step explanation:
The car braked with a constant deceleration of 16ft/s^2. This is a negative acceleration. Therefore,
a = - 16ft/s^2
While decelerating, the car produced skid marks measuring 200 feet before coming to a stop.
This means that it travelled a distance,
s = 200 feet
We want to determine how fast the car was traveling (in ft/s) when the brakes were first applied. This is the car's initial velocity, u.
Since the car came to a stop, its final velocity, v = 0
Applying Newton's equation of motion,
v^2 = u^2 + 2as
0 = u^2 - 2 × 16 × 200
u^2 = 6400
u = √6400
u = 80 ft/s
Answer:
<h2>a = 16</h2>
Step-by-step explanation:
Look at the picture.
The formula of an area of a trapezoid is:
- bases
- height
We have:
Substitute:
<em>divide both sides by 8</em>
Answer:
<em>The SUV is running at 70 km/h</em>
Step-by-step explanation:
<u>Speed As Rate Of Change
</u>
The speed can be understood as the rate of change of the distance in time. When the distance increases with time, the speed is positive and vice-versa. The instantaneous rate of change of the distance allows us to find the speed as a function of time.
This is the situation. A police car is 0.6 Km above the intersection and is approaching it at 60 km/h. Since the distance is decreasing, this speed is negative. On the other side, the SUV is 0.8 km east of intersection running from the police. The distance is increasing, so the speed should be positive. The distance traveled by the police car (y) and the distance traveled by the SUV (x) form a right triangle whose hypotenuse is the distance between them (d). We have:
To find the instant speeds, we need to compute the derivative of d respect to the time (t). Since d,x, and y depend on time, we apply the chain rule as follows:
Where x' is the speed of the SUV and y' is the speed of the police car (y'=-60 km/h)
We'll compute :
We know d'=20 km/h, so we can solve for x' and find the speed of the SUV
Thus we have
Solving for x'
Since y'=-60
The SUV is running at 70 km/h
Answer:
Hiiiii
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