Q: A 1200 kg car is moving at a constant speed of 20 m/s on a flat road. The total resistive force (from friction and air drag) acting on the car is 800 N. What is the magnitude of the engine's thrust force?

$$F_{\text{thrust}} = 800\ \text{N}$$

Q: A 10 kg box is at rest on a horizontal surface. The coefficient of static friction between the box and the surface is $$\mu_s = 0.4. $$What is the maximum horizontal force that can be applied before the box starts to move?

$$F_{\text{max}} = 39.2\ \text{N}$$

Question 1

A 1200 kg car is moving at a constant speed of 20 m/s on a flat road. The total resistive force (from friction and air drag) acting on the car is 800 N. What is the magnitude of the engine's thrust force?

Accepted Answer

$$F_{	ext{thrust}} = 800\ 	ext{N}$$

Question 2

A ball of mass 0.5 kg is attached to a string and swung in a horizontal circle of radius 1.2 m at a constant speed of 3 m/s. What is the tension in the string?

Accepted Answer

$$T = 3.1\ 	ext{N}$$

Question 3

Which of the following statements best describes Newton's Third Law?

Accepted Answer

For every force, there is an equal and opposite force acting on a different object.

Question 4

A 10 kg box is at rest on a horizontal surface. The coefficient of static friction between the box and the surface is $$\mu_s = 0.4. $$What is the maximum horizontal force that can be applied before the box starts to move?

Accepted Answer

$$F_{	ext{max}} = 39.2\ 	ext{N}$$

Question 5

A skydiver of mass 80 kg reaches terminal speed during free fall. If the drag force is given by $$D = \frac{1}{2}C\rho A v^2$ and the drag coefficient, air density, and cross-sectional area are constant, which of the following is true at terminal speed?

Accepted Answer

The drag force equals the gravitational force.

Question 6

A 2 kg object is moving in a circle of radius 0.5 m with a constant angular speed of $$4\ 	ext{rad/s}. $$What is the magnitude of the radial (centripetal) acceleration?

Accepted Answer

$$a_r = 16\ 	ext{m/s}^2$$

Question 7

A block slides down a ramp inclined at $$30^\circ to $$the horizontal. The coefficient of kinetic friction is $$\mu_k = 0.2. $$What is the acceleration of the block?

Accepted Answer

$$a = g(\sin 30^\circ - \mu_k \cos 30^\circ)$$

Question 8

A 5 kg object is acted on by two forces: $$F_1 = 10$$\ 	ext{N}$$ east and F_2$ = 6\ 	ext{N}$$ north. What is the magnitude of the object's acceleration?

Accepted Answer

$$a = 3.2\ 	ext{m/s}^2$$

Question 9

A 1.5 kg ball is dropped from rest from a height of 20 m. Neglecting air resistance, what is its speed just before hitting the ground?

Accepted Answer

$$v = 19.8\ 	ext{m/s}$$

Question 10

A 2 kg object moves in a circle of radius 3 m at a constant speed of 6 m/s. What is the magnitude of the net force acting on the object?

Accepted Answer

$$F = 24\ 	ext{N}$$

Question 11

A 70 kg astronaut weighs 686 N on Earth. What would be the astronaut's weight on the Moon, where $$g_{	ext{moon}} = 1.62\ 	ext{m/s}^2$$?

Accepted Answer

$$W = 113.4\ 	ext{N}$$

Question 12

A 0.2 kg puck slides on a frictionless horizontal surface at 5 m/s. It collides elastically with a stationary 0.3 kg puck. What is the velocity of the 0.2 kg puck after the collision?

Accepted Answer

$$v = -1\ 	ext{m/s}$$

Question 13

A 10 kg mass is suspended by two ropes, one making a $$60^\circ$$ angle with the ceiling and the other a $$45^\circ$$ angle. What is the tension in the rope at $$60^\circ$$?

Accepted Answer

$$T = 84.9\ 	ext{N}$$

Question 14

A cyclist rounds a curve of radius 50 m at a speed of 10 m/s. What is the minimum coefficient of static friction required to prevent slipping?

Accepted Answer

$$\mu_s = 0.2$$

Question 15

A 0.5 kg object is attached to a string and whirled in a vertical circle of radius 2 m. What is the minimum speed at the top of the circle so the string remains taut?

Accepted Answer

$$v = 3.13\ 	ext{m/s}$$

Question 16

A 1.0 kg object is acted on by a force $$F = 4t N$$, where $$t is in $$seconds. If the object starts from rest, what is its velocity after 3 seconds?

Accepted Answer

$$v = 12\ 	ext{m/s}$$

Question 17

A 2 kg block is pushed up a frictionless incline at $$30^\circ$$ with an initial speed of 8 m/s. How far up the incline does the block travel before coming to rest?

Accepted Answer

$$d = 3.27\ 	ext{m}$$

Question 18

Which of the following is NOT a correct SI unit for the given quantity?

Accepted Answer

Weight: $$	ext{kg}$$

Question 19

A 0.8 kg object moves in a circle of radius 0.4 m with a tangential acceleration of $$2\ 	ext{m/s}^2$$ and an angular velocity of $$5\ 	ext{rad/s}. $$What is the magnitude of the total acceleration?

Accepted Answer

$$a = 10.2\ 	ext{m/s}^2$$

Comprehensive Study Guide: Newtonian Mechanics and Circular Motion (Chapters 5–8)

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