Question

$\Huge{\textbf{\textsf{{\color{navy}{QuɆ}}{\purple{sTi}}{\pink{Øn}}{\color{pink}{:}}}}}$

A bullet fired with a speed of 50 ms ⁻¹ is stopped at
a depth of 10 cm by a wall. What is the retardation
offered by the wall?
​

Answer 1

$\huge\underline\pink{Question}$

A bullet fired with a speed of 50 ms ⁻¹ is stopped at

a depth of 10 cm by a wall. What is the retardation

offered by the wall?

$\huge\underline\pink{Required\:Answer}$

The resistance offered will be expressed in terms of retardation or negative acceleration (m/s²)

To find the resistance we use the 3rd equation of motion

v2=u2+2as

v = final velocity

u = initial velocity

a = acceleration (the unknown variable)

s = displacement

After plugging in the values we get this linear equation

0=502+2(0.1)a

v is 0 as the bullet has stopped and displacement is 0.1 because 10 cm is converted to metres

Solving this equation

a=−12500m/s²

Therefore the wall retards the bullet by 12500m/s² or the resistance offered by the wall is 12500m/s²

Note: the mass of the bullet wont affect the answer and is just given to throw you off track I suppose

As the unit of resistance isn't specified in the question the mass can be multiplied with the retardation to find the resistance in terms of Newtons

The answer comes out to be -50 Newtons therefore the resistance offered is 50 Newtons