Answer: acceleration is equal to the change in velocity per unit time in seconds.
a= ∆v / t = vf - vi / t
Explanation: change in velocity or ∆v can be expressed as (vf - vi)
Answer:
One positive and one negative
Machines makes work easier by increasing the amount of force that is applied, and changing the direction in which the force is applied !! Hope it helped (p.s. I had this same question)
Answer:

Given:
Initial velocity (u) = 30 m/s
Final speed (v) = 0 m/s
Acceleration (a) = - 1.5 m/,s²
To Find:
Time in which train will come to rest (t).
Explanation:

So,
Time in which train will come to rest = 20 seconds
Answer:(a)9.685 mm
(b)4.184 mm
Explanation:
Given
Wavelength of light 
Width of slit(b)=0.210
(a)Width of central maximum located 1.80m from slit


=9.685 mm
(b)Width of the first order bright fringe


