Question

A- what constant acceleration, in SI units, must a car have to gofrom zero to 60 mph in 10 s?

Answer 1

Answer:

a) acceleration a = 2.68 m/s^2

b) fraction of g = 0.273 or 27.3%

c) distance travelled d = 134m (in SI unit)

d = 439.5ft (in feet)

Explanation:

a) converting 60mph (miles per hour) to m/s

∆v = 60 miles/hour × 1609.344meters/mile × 1/3600 seconds/hour

∆v = 26.82m/s

t = 10s

acceleration = change in velocity/time = ∆v/t

Acceleration a = 26.82/10 = 2.68m/s^2

b) acceleration due to gravity is g = 9.8m/s^2

Fraction of g = a/g = 2.68/9.8 = 0.273

Fraction = 0.273 or 27.3%

c) distance travelled can be calculated using the equation below.

d = ut + 0.5at^2 ....1

Initial speed u = 0

time t = 10s

Acceleration a = 2.68m/s^2

d = distance covered.

From equation 1, putting u = 0

d = 0.5at^2

d = 0.5(2.68 × 10^2)

d = 134m

Converting meters to feet

d = 134m × 3.28ft/m

d = 439.5ft

Answer 2

Answer:

(a) 0.017m/s^2

(b) 17/100,000

(c) 0.17m, 0.558ft

Explanation:

(a) speed = 60mph = 60m/1h × 1h/3600s = 0.017m/s, time = 10s

Acceleration (a) = speed ÷ time = 0.017m/s ÷ 10s = 0.0017m/s^2

(b) g = 9.8m/s^2, a = 0.0017m/s^2

a/g = 0.0017/9.8 = 0.00017 = 17/100,000

(c) Distance = speed × time = 0.017m/s × 10s = 0.17m

Distance in foot = 0.17 × 3.2808ft = 0.558ft