Question

A bike is travelling at a velocity of 7 m/s. The cyclist brakes for 2 seconds when a dog runs out in front of her. The bikes new velocity is 4m/s. Calculate the acceleration of the bike

Answer 1

Acceleration=Δv/Δt=(final velocity-initial velocity)/time taken

Initial velocity =7m/s
Final velocity=4m/s
Time=2sec

It would decelerate

Answer 2

For an acceleration of a
v(t) = at + c
initial velocity = 7 m/s
7 = a(0) + c
so v(t) = at + 7
when t = 2, v(2) = 4
4 = 2a + 7
2a = -3
a = -3/2

The bike decelerated at 3/2 m/s^2 or it accelerated at -3/2 m/s^2

Answer 3

V = Vo + a*T
4 = 7 + a*2
a = -3/2 = -1.5 m/s^2.

Answer 4

-1.5

trust me on this one :)