Alex, who has a mass of 100 kg, is skateboarding at 9.0 m/s when he smacks into a brick wall and comes to a dead stop in 0.2 s. a. show that his deceleration is 45 m/sz. b. show that the force ofimpact is 4500 n. (ouch! )

A. The deceleration of Alex is 45 m/s²

B. The force of impact is 4500 N

From the question given above, the following data were obtained:

a = (v – u) / t

a = (0 – 9) / 0.2

a = –9 / 0.2

a = –45 m/s²

The, negative sign indicate that the Alex is coming to rest.

F = ma

F = 100 × 45

F = 4500 N

Learn more about acceleration:

link

Part a)

acceleration is defined as rate of change in velocity

so we can write

here we know that

finally it will stop so vf = 0

initial speed is given as 9m/s

and the time to stop is 0.2 s

Part b)

Now by 2nd law of Newton

given that

m = 100 kg

a = 45 m/s^2

so now using above equation

so it will exert 4500 N force to stop

  1.the balanced   chemical equation is as below

cu +   2 ag(no)₃ → cu(no₃)₂   +2 ag

2.the   much silver   produced   is   50.9 g

step 1: find the   moles of cu

moles =   mass÷   molar mass

  from periodic table the molar mass of cu = 63.5 g/mol

moles is therefore = 15.00 g÷ 63.5 g/mol = 0.236   moles

step 2: use the mole ratio to determine the   moles of ag

from equation above   cu: ag   is 1: 2

therefore the moles of ag   =0.236   moles   x 2/1 =0.472   moles

step 3: find the mass   of ag

mass = moles x molar mass

from periodic table   the molar mass of ag =107.87 g/mol

mass   = 0.472   moles x 107.87 g/mol = 50.9 g

3.   the   much   silver   collected worth is   1.797 oz

  convert   50.9 g   to oz

that is   1 gram = 0.0353 oz

          50.9 grams =?   oz

by cross multiplication

={(50.9 grams x 0.0353 oz) / 1   gram}   =1.797 oz