Q1) An aeroplane covers a certain distance at a speed of 240 kmph in 5 hours.To cover the same distance in 1(2/3) hours, it must
travel at a speed of;
A)300kmph
B)360kmph
C)600kmph
D)720kmph
Explain how you got the answer
A)300kmph
B)360kmph
C)600kmph
D)720kmph
Explain how you got the answer
1 answer:
Answer:
D) 720 kmph
Explanation:
First, let's find what distance this aeroplane covered. Distance (d) is the product of speed and time - here, we have a speed of 240 kmph and a time of 5 hours, gives us
km
Using that same fact, we can set up a new equation to solve for speed (s) when we have a distance of 1200 km and a time of 1 2/3 hours. For the sake of cleanliness, I'm gonna rewrite 1 2/3 as the improper fraction 5/3:
Multiplying both sides of the equation by 3/5:
kmph
So our answer is D.
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Answer:
The time it will take for the object to hit the ground will be 4.
Explanation:
You have:
h(t)=−16t²+v0*t+h0
Being v0 the initial velocity (54 ft/s) and h0 the initial height (40 ft) and replacing you get:
h(t)=−16t²+54*t+40
To know how long it will take for the object to touch the ground, the height h(t) must be zero. So:
0=−16t²+54*t+40
Being a quadratic function or parabola: f (x) = a*x² + b*x + c, the roots or zeros of the quadratic function are those values of x for which the expression is 0. Graphically, the roots correspond to the points where the parabola intersects the x axis. To calculate the roots the expression is used:
In this case you have that:
- a=-16
- b= 54
- c= 40
Replacing in the expression of the calculation of roots you get:
Expresion (A)
and
Expresion (B)
Solving the Expresion (A):
Solving the Expresion (B):
These results indicate the time it will take for the object to hit the ground can be -5/8 and 4. Since the time cannot be negative, then <u><em>the time it will take for the object to hit the ground will be 4.</em></u>