Question

*URGENT*

1. What is the force of sliding friction between a block and the ground if the coefficient of kinetic friction is μk = 0.28 and the block weighs 17 N?

a. 81 N
b. 17 N
c. 4.8 N
d. 61 N
e. 1.3 N


2. A 300 kg spacecraft weighs 760 N on the surface of Planet Zphyz. What is the acceleration due to gravity on the planet’s surface?

a. 6.0 m/s^2
b. 2.5 m/s^2
c. 5.1 m/s^2
d. 0.0 m/s^2
e. 0.39 m/s^2


3. A 4900 kg jet reaches a takeoff velocity of 90 m/s after accelerating from rest for 800 m down the runway. What net force is required from the jet's engines?

a. 970 N
b. 44000 N
c. 3.5 x10^8 N
d. 25000 N
e. 50000 N


4. The coefficient of kinetic friction between a floor and a box made of wood is μk = 0.13. How far does the box slide if it has an initial speed of vo = 5.0 m/s?

a. 29 m
b. 9.8 m
c. 39 m
d. 17 m
e. 11 m


5. What is the acceleration due to gravity on Planet X if someone who weighs 900 N on Earth weighs 2400 N on Planet X?

a. 26 m/s^2
b. 3.7 m/s^2
c. 9.8 m/s^2
d. 92 m/s^2
e. 240 m/s^2


6. A 2.4 kg box is moving at 21 m/s on a frictionless plane. When will it stop?

a. 23
b. never s
c. 0.11 s
d. 8.8 s
e. immediately

Answer 1

Answer: c) 4.8 N

Explanation: In order to explian this value, we have to take into account the definition of the friction force which is given by:

f<= μk*N so we have: in a horizontal plane the normal force;

N=Weight (m*g)

f=0.28*17N=4.76 N