Question

Dave and Alex push on opposite ends of a car that has a mass of 875 kg. Dave pushes the car to the right with a force of 250 N, and Alex pushes to the left with a force of 315 N. Assume there is no friction.

a. Draw a free-body diagram showing all the forces acting on the car.

b. What is the net force on the car in the x-direction?

c. What is the acceleration of the car?

d. What is the normal force acting on the car?

Answer 1

see if you can sketch the fbd

let the car be a dot and draw one arrow representing the left force and the other representing the right force

Answer 2

:/

Answer 3

good, now add the upward arrow for the normal force and downward from gravity

Answer 4

that would be part b right?

Answer 5

we're still on a ^^

Answer 6

good, now we just label the arrows with the names/values given in the problem

Answer 7

that's it for a)

what's the net force in the x-direction for b?

Answer 8

wouldn't i need to solve 875*9.8 for part a

Answer 9

sure, you can simplify it if you want, I was just demonstrating how to do the labels ^^ it's not super important

Answer 10

so 8575

Answer 11

yeah 8575 N

Answer 12

okay now for b

Answer 13

calculate the net force in the x-direction only

Answer 14

um that would be what formula?

Answer 15

you have a force going to the right + 250N
you have a force going to the left - 315

250 - 315 = ?

Answer 16

-65

Answer 17

good so 65N left

Answer 18

for c) calculate acceleration using newton's 2nd law

Answer 19

f=ma=875*9.8

Answer 20

8575N

Answer 21

we calculated the net force as 65

you are solving for acceleration

Answer 22

oh okay
65=873*a

Answer 23

good a = ?

Answer 24

0.074

Answer 25

good, sinc it's going to the left -0.074 m/s/s

Answer 26

d) normal force and gravity cancel out so normal force = gravity = mg

Answer 27

875*

Answer 28

is the gravity 9.8?

Answer 29

yes

Answer 30

oh so 8575N

Answer 31

good, that's it