Question

You have a wooden bench in your living room. You set your backpack on the bench and lean your hand against the wall. Name two action-reaction pairs that are present in this situation.

Answer 1

@Vocaloid @StraightLine @Nnesha @sillybilly123

Answer 2

backpack on the bench

1. downward force of gravity from the weight of the backpack on the bench
2. normal force upwards from the bench on the backpack

hand on the wall
1. hand pressing against wall
2. wall pushing back against hand

Answer 3

You push a shopping cart full of groceries. The shopping cart has a mass of 32 kg.

a. What is the weight of your shopping cart?




b. How much force must you apply to give the cart an acceleration of 1.3 m/s2?




c. If you push with a force of 200 N, what is the acceleration of the cart?








d. You are driving home from the store. If your car has an acceleration of 4.1 m/s2, and its engine is applying a forward force of 7000 N, what is the mass of your car?

Answer 4

a) weight = mg as usual
for b-d use F = ma and solve for the appropriate variable, make sure your units make sense

Answer 5

still there?

Answer 6

a.313.6
b.32/1.3=24.62N
c.200/32=6.25 m/s
7000/4.1=1707.32

Answer 7

for d kg as the measurement

Answer 8

check b again

F = ma

Answer 9

a.313.6
b.32/1.3=41.6N
c.200/32=6.25 m/s
7000/4.1=1707.32kg

Answer 10

good just change acceleration to m/s/s

Answer 11

also weight needs to be Newtons

Answer 12

a.313.6 N
b.32/1.3=41.6N
c.200/32=6.25 m/s/s
7000/4.1=1707.32kg

Answer 13

good

Answer 14

You have a ball with mass 1.3 kg tied to a rope, and you spin it in a circle of radius 1.8 m. If the ball is moving at a speed of 3 m/s, what is the centripetal force acting on the ball?

Answer 15

mv^2/r

Answer 16

1.3(3)^2/1.8

Answer 17

good

Answer 18

6.5N

Answer 19

good

Answer 20

Andrew and Warren sit on opposite sides of a table of mass 28 kg. Andrew pushes the table to the right with a force of 277 N, and Warren pushes the table to the left with a force of 215 N. (Assume there is no friction.)

a. Draw the free-body diagram of the table. (You do not need to draw it perfectly to scale. Just make sure the directions are correct.)

b. Write the expression for the net force on the table along the y-axis.

c. Write the expression for the net force on the table along the x-axis.

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

e. What is the net force on the table along the x-axis, including direction?

f. What is the acceleration of the table, including direction?

Answer 21

your fbd should have 4 forces: normal force, gravity, left force, right force

Answer 22

don't forget the normal force + weight force

Answer 23

that would be up and down right

Answer 24

yes

Answer 25

good, just be sure to label them as Fn and Fg

Answer 26

for b) net force in y = 0 = Fn - Fg
c) net force in x = right force - left force = 277-215N

Answer 27

y = 0 = Fn - F(9.8)

Answer 28

right force - left force = 277-215N=62N

Answer 29

Fg = mg

y = 0 = Fn - Fg = Fn - (28)(9.8) = 0

they don't ask you to solve for normal force yet (that's in part d) so just leave it like this if you want

Answer 30

b. Write the expression for the net force on the table along the y-axis. (2 points)
y = 0 = Fn - Fg = Fn - (28)(9.8) = 0
c. Write the expression for the net force on the table along the x-axis. (2 points)
right force - left force = 277-215N=62N

Answer 31

good

for d) we know that 0 = Fn - (28)(9.8) so solve for Fn

Answer 32

0 = F-(28)(9.8)
Fn=274.4

Answer 33

good (force is almost always Newtons as usual)

Answer 34

alright so for E, 62n right

Answer 35

good

for f) just use f = ma with that 62N force and the 28kg mass to find accelerationo

remember that units are m/s/s

probably need to go after this

Answer 36

102.21m/s/s

Answer 37

Thanks!

Answer 38

other way around, you need to divide a = F/m

Answer 39

2.21m/s/s

Answer 40

as a quick tip you want to check that your answers make sense in real life, 102.21 m/s/s is approaching the speed of sound

2.21 m/s/s is correct

Answer 41

Yeah i should probably do that :O