Question

A 1.2-kg object moving with a speed of 8.0 m/s collides perpendicularly with a wall and emerges with a speed of 6.0 m/s in the opposite direction. If the object is in contact with the wall for 2.0 ms, what is the magnitude of the average force on the object by the wall?

a. 9.8 kN.
b. 8.4 kN.
c. 7.7 kN.
d. 9.1 kN.
e. 1.2 kN.

Answer 1

Given that,

Mass of the object, m = 1.2 kg

Initial speed of the object, u = 8 m/s

Final speed of the object, v = -6 m/s (in opposite direction)

Time, t = 2 ms

To find,

The average force on the object by the wall.

Solution,

Let F be the force. Using Newton's second law of motion,

F = ma, a is acceleration

`F=(m(v-u))/(t)\\\\F=(1.2* ((-6)-8))/(2* 10^(-3))\\\\=8400\ N`

or

F = 8.4 N

So, the magnitude of average force in the object by the wall is 8.4 N.