Download Chap4 force practice problems with answers

PRACTICE PROBLEMS CHAPTER 4
NAME __________________________________
1. A 7.00 kg bowling ball experiences a net force of 5.00 N. What will be its acceleration?
2. An astronaut applies a force of 500. N to an asteroid and it accelerates at 7.00 m/s2. What is the asteroid’s mass?
3. Two ropes are attached to a 40.0 kg object. The first rope applies a force of 25.0 N and the second a force of 40.0 N. If the two ropes are
perpendicular to each other, what is the resultant acceleration of the object?
4.
Acceleration due to gravity on the moon’s surface is 1/6th that on Earth. An astronaut’s life support backpack weighs 300. lb on Earth. In
pounds, what does it weigh on the moon?
5.
An 8.00 kg rock is rolled in the sand. It starts at 5.00 m/s, moves in a straight line for a distance of 3.00 m, and then stops. What is its
average acceleration? What was the average force acting on the rock as it slowed down?
6.
Rita accelerates a 0.400 kg ball from rest to 9.00 m/s during the 0.150 s in which her foot is in contact with the ball. What average force
does she apply to the ball during the kick?
7.
An elevator weighing 20,000. N is supported by a steel cable. What is the tension in the cable when the elevator is being accelerated
upward at a rate of 3.00 m/s2? (g = 9.80 m/s2)
8.
An automobile of mass 2000. kg moving at 30.0 m/s, is braked suddenly, with a constant braking force of 10,000. N. How far does the car
travel before stopping?
9.
A shot-putter moves his arm and the 7.00 kg shot through a distance of 1.00 m, giving the shot a velocity of 10.0 m/s from rest. Find the
average force exerted on the shot during this time.
Σ𝐹 = 𝑚𝑎
𝑊 = 𝑚𝑔
10. A baseball batter hits an incoming 40.0 m/s fastball. The ball leaves the bat at 50.0 m/s after a ball-on-bat contact time of 0.0300 s. What is
the force exerted on the 0.150 kg baseball?
11. Two forces, F1 and F2 act on a 5.00 kg object. F1 = 10.0 N east. F2 = 20.0 N south.
A) What is the net force that acts on the object?
B)
What is the object’s acceleration?
12. Two forces, F1 and F2 act on a 5.00 kg object. F1 = 12.0 N north. The object's acceleration is 15.0 m/s2 to the west. Calculate F2.
13. A 1000. kg car drives on a highway with a constant velocity of 45.0 m/s to the west. Determine the amount of net force acting on the car.
14) An 80.0 kg man is standing on a scale in an elevator. The scale reads force in Newtons. What is the reading on the scale in each of the
following situations:
a) The elevator is holding still
b) The elevator is beginning to move upward with an upward acceleration of 1.50 m/s2
c) The elevator moves upward with a constant speed of 3.00 m/s
c) As it nears the intended floor, the elevator slows down as it is going up. The acceleration has a magnitude of 2.00 m/s2
d) The elevator starts its downward motion with an acceleration of 1.80 m/s2
e) The elevator goes down at a constant speed of 4.00 m/s
f) As it nears its intended stop, the elevator slows down while going down. It has an acceleration with a magnitude of 2.20 m/s2
g) The elevator cable snaps and the elevator goes into freefall.
o
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Answers: 1) 0.714 m/s2; 2) 71.4 kg; 3) 1.18 m/s2 @ 32o from 40 N force; 4) 50 lbs; 5) 4.17 m/s2; -33.3 N; 6) 24 N; 7) 26,100 N; 8) 90 m; 9) 350 N; 10) 450 N; 11) a) 22.4 N @ 63.4 S of E; b) 4.47 m/s in
same dir ; 12) 75.9 N @ 9.09o S of W; 13) 0; 14) a) 784 N; b) 904 N; c) 784 N; c2) 624 N; d) 640 N; e) 784 N; f) 960 N; g) 0
Σ𝐹 = 𝑚𝑎
𝑊 = 𝑚𝑔