Question

A hockey puck is hit on a frozen lake and starts moving with a speed of 13 m/s. Seven seconds later, its speed is 6.7 m/s. What is its average acceleration? The acceleration of gravity is 9.8 m/s 2 . Answer in units of m/s 2 .

Answer 1

-0.9 m/s²

Step-by-step explanation:

t = Time taken by the hockey puck = 7 seconds

u = Initial velocity of the hockey puck = 13 m/s

v = Final velocity of the hockey puck = 6.7 m/s

a = Acceleration of the hockey puck

Equation of motion

`v=u+at\\\Rightarrow a=(v-u)/(t)\\\Rightarrow a=(6.7-13)/(7)\\\Rightarrow a=-0.9\ m/s^2`

The acceleration of the hockey puck in the seven seconds is -0.9 m/s²

The acceleration due to gravity is not needed to find the acceleration of the puck.