Question

A stone is dropped from the window of a bus moving at 72 kmh¹ on the road . If the window is 2.0 m high , determine the distance along the road where the stone will strike the road . Use g = 10 ms². ​

Answer 1

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Let's get our units consistent.

Acceleration due to gravity:

g

=

9.8

m

s

2

Speed:

60

k

m

h

r

⋅

1000

m

1

k

m

⋅

1

h

r

3600

s

=

16.67

m

s

Distance to fall:

196

c

m

⋅

1

m

100

c

m

=

1.96

m

We need the time to hit the ground, so we need the formula

y

=

u

⋅

t

+

1

2

⋅

a

⋅

t

2

1.96

m

=

0

+

1

2

⋅

9.8

m

s

2

⋅

t

2

t

2

=

2

⋅

1.96

m

9.8

m

s

2

=

0.4

s

2

t

=

0.632

s

Now we can calculate the distance down the road it travels in that time. It is

d

=

16.67

m

s

⋅

0.632

s

=

10.5

m

Answer 2

Answer:

A stone is dropped from the window of a bus moving at 72 kmh¹ on the road . If the window is 2.0 m high , determine the distance along the road where the stone will strike the road . Use g = 10 ms².