Ahockey 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 .

-0.9 m/s²

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

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.

think about the oscillation of the toy shown in the video. when the toy is at the highest point of its motion, its velocity is zero and its acceleration is negative.