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Question 357092: Hi, i need help with those questions am practicing but i dont understand how to work out the rearrangement etc. please show your working out clearly many thanks,
1. The speed of a car after t seconds is given by the formula v= u + at where u is the starting speed in metres per second (m s-¹) and a is the acceleration in metres per second per second (ms-2).
a) A car joins a motorway at a speed of 25 ms-1 and accelerates at 0.65 ms -² for 12 seconds. Find its speed at the end of this time.
b) Rearrange this formula to make the subject (i) u (ii) t
2. if a ball is thrown up in the air at a velocity of v, the height it reaches is given by h = V2/2g
Where g is the acceleration due to gravity.
a) Find the height reached by a ball thrown up at a velocity of 15 ms-1.
b) B) Rearrange this formula to make the subject v.
3. A formula for converting temperature is C=5/9(F- 32)
Where C is the temperature in degree Celsius and F is the temperature in degrees Fahrenheit
a)An old recipe gives the oven temperature 375° F. Covert this temperature to Celsius.
b)Rearrange this formula to make the subject F.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! 1. The speed of a car after t seconds is given by the formula v= u + at where u is the starting speed in metres per second (m s-¹) and a is the acceleration in metres per second per second (ms-2).
a) A car joins a motorway at a speed of 25 ms-1 and accelerates at 0.65 ms -² for 12 seconds. Find its speed at the end of this time.
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v = u + at
v = 25 m/s + 0.65/s^2(12)
v = 25 + 7.8
velocity = 32.8 meters/sec
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b) Rearrange this formula to make the subject
(i) u = v - at
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(ii) t = (v-u)/a
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2. if a ball is thrown up in the air at a velocity of v, the height it reaches is given by h = V^2/2g
Where g is the acceleration due to gravity.
a) Find the height reached by a ball thrown up at a velocity of 15 ms-1.
h(v) = 15^2/(2g)
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b) B) Rearrange this formula to make the subject v.
V = sqrt(2gh)
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3. A formula for converting temperature is C=(5/9)(F)- 32
Where C is the temperature in degree Celsius and F is the temperature in degrees Fahrenheit
a)An old recipe gives the oven temperature 375° F. Covert this temperature to Celsius.
C(375) = (5/9)(375) - 32 = 176 1/3
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b)Rearrange this formula to make the subject F.
C+32 = (5/9)F
F = (9/5)(C+32)
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Cheers,
Stan H.
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