grade 11 physics

posted by .

Cathy takes the bus home from work. In her hand she holds a 2 kg cake box, tied together with a string. As she ascends the steps into the bus,the box accelerates upward at a rate of 2.5m/s^2. what is the force exerted on the string?

Fg=ma
=2*9.8
=19.6N

Fn=ma-Fg
=2*2.5-(-19.6)
=24.6N

b)she sets the box on the seat beside her. the bus acelerates from rest to 60 km/h in 4 s and the box begins to slide. What's the coefficient ofstatic friction b/w the box and te bus seat?

Ff=m*Fn
=2(24.6)
=49.2N

static coefficient=Ff/Fn
=49.2/24.6
=2

c)a taxi suddenly cuts infront of the bus, causing the bus driver to slam on the brakes. The bus driver reduces the speed from 60 km/h to 20 km/h in 1.5 s. Does Cathy's cake slide forward?
I have no idea how to even start with this one.

  • grade 11 physics -

    I am taking this course and am confused with this question... in the second part to(a),why does 19.6 become negative to get 24.6?
    If it accelerating upward wouldn't 19.6 be positive making the answer
    2(2.5)-19.6
    =-14.6N
    ???

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. 6th grade math

    Mya works on Saturdays and then attends a study group. She needs to be home before her younger brother. She walks from work to the study group in 5 minutes. She studies for 40 minutes. She takes 5 minutes to walk to the bus stop. The …
  2. college physics

    As your bus rounds a flat curve at constant speed, a package with mass .5 kg, suspended from the luggage compartment of the bus by a string 45 cm long, is found to hang at rest relative to the bus, with the string making an angle of …
  3. Physics

    A bus starts from rest at a bus stop and accelerates at a rate of 1.12 m/s^2 for 11.0s. It runs at constant speed for 80.0 s and slows at a rate 1.20 m/s^2 until it stops at the next bus stop. (a) What is the maximum speed attained. …
  4. physics

    You are riding in a school bus. As the bus rounds a flat curve at constant speed, a lunch box with a mass of 0.470 suspended from the ceiling of the bus by a string of length 1.85 is found to hang at rest relative to the bus when the …
  5. math

    There is a bus stop in front of Luann's house.A bus arrives at the stop every 45 minutes and goes into fown.The first bus comes at 7:15am If the bus trip takes 12 minutes, what is the latest bus Luann can take in order to get to town …
  6. AP Physics

    Jack is 12m from the bus and is running towards the bus at a constant 4.0m/s. If the bus accelerates away from the bus stop at .8m/s^2, can he catch the bus?
  7. Physics? clueless on what to do

    Jack is 12m from the bus and is running towards the bus at a constant 4.0m/s. If the bus accelerates away from the bus stop at .8m/s^2, can he catch the bus?
  8. Physics

    You are riding in a school bus. As the bus rounds a flat curve at constant speed, a lunch box with a mass of 0.550 suspended from the ceiling of the bus by a string of length 1.77 is found to hang at rest relative to the bus when the …
  9. Physics

    Traveling in the city its faster to take a bicycle than a bus, one reason for this is that a bike can accelerate faster than a bus. Let’s say a Bike and bus both stopped at a red light and both takes off an exact same time when the …
  10. English

    1. He was late because he missed the bus. [In this sentence, what does 'the bus' mean?

More Similar Questions