Question

The Eiffel Tower is 301 m high. A coin is thrown vertically upwards from the top of the tower with an initial velocity of 5.00 m⋅s−1
How long will it take for the coin to strike the ground? Ignore the effects of air resistance and give your answer in seconds to three significant figures, including a unit. Take acceleration due to gravity, g, as 9.81 m s-2.

Answer 1

ANSWER

s=ut+

2

1

at

2

=19.6×5−

2

1

×9.8×5

2

=−24.5 m

Hence, height of tower =24.5m

v=u+at

=19.6−9.8×5=−29.4 m/s

Answer 2

Given: The height of the Eiffel tower$=301m.$

The initial velocity$u=5.00ms^{-1}$

We have to find the time taken by coin to strike the ground.

For this, we are using the formula$\mathrm{s}=\mathrm{ut}+\frac{1}{2} \mathrm{at}^{2}$.

Now,

$=>\mathrm{s}=\mathrm{ut}+\frac{1}{2} \mathrm{at}^{2}\\\\=>301=5\times t+\frac{1}{2} \times9.81\times t^{2} \\\\=>10t+9.81t^{2} =602\\=>9.81t^{2}+10t=602$

By solving the quadratic equation we get,

$t=7.340or -8.359$

As we know that the time is never negative so the answer is $t=7.34s.$

Hence, the time taken by the coin to strike the ground will be $7.34s.$