Vectors
Describe what is meant by a vector in physics
A quantity that has both magnitude and direction
Which assumption is usually made about air resistance in ideal projectile motion problems?
A. It is ignored
B. It increases linearly with velocity
C. It reverses gravity
D. It has no direction
A - It is ignored
Which component of gravitational force pulls an object down the incline?
mg sinθ
What provides centripetal force in a car turning a flat curve?
A. Gravity
B. Friction
C. Normal force
D. Engine thrust
Which of the following best describes Kepler’s Third Law of Planetary Motion?
A. Planets move in circular orbits around the Sun.
B. The square of a planet’s orbital period is proportional to the cube of its average orbital radius.
C. A line joining a planet and the Sun sweeps out equal areas in equal times.
D. The orbital speed of all planets is constant.
B. The square of a planet’s orbital period is proportional to the cube of its average orbital radius.
If a displacement of 8 m north is combined with 6 m east, what is the magnitude of the resultant vector?
10 m
A projectile is launched at 20 m/s horizontally from a 45 m cliff. How long until it lands?
3.03 s
Determine the parallel component of weight for a 10 kg block on a 20° incline
33.5 N
An object moves at 15 m/s in a circle of radius 5 m. What is centripetal acceleration?
45m/s^2
Gravitational force between two 1000 kg masses 2 m apart
1.7×10⁻⁵ N.
Why can’t scalars and vectors be added in the same way?
Vectors require both direction and magnitude
A projectile is launched at 20 m/s horizontally from a 45 m cliff. What is the horizontal range?
60 m
A 6 kg box slides down a frictionless incline of angle 30°. What is the net force acting on the box along the incline?
29.4 N
A 2 kg mass moves in a circle (r = 4 m) at 10 m/s. What is centripetal force?
50 N
A planet orbits a star at an average distance of 4 × 10¹¹ m. Another planet orbits the same star at twice this distance. Using Kepler’s Third Law, how does the orbital period of the second planet compare to the first?
It is 2.83 times longer
A force of 20 N acts at 60° above the horizontal. What is the horizontal component?
10 N
Why is horizontal velocity constant in projectile motion?
Gravity only acts vertically
Why is the normal force smaller than mg on an incline?
A. Friction cancels part of it
B. Normal force balances only perpendicular component of weight
C. Gravity decreases on slopes
D. Normal force includes horizontal forces
B - Normal force balances only perpendicular component of weight
Why is centripetal force not a separate type of force?
A. It is gravity only
B. It is the name given to whichever real force acts toward the centre
C. It is caused by acceleration
D. It cancels inertia
B - It is the name given to whichever real force acts toward the centre
Earth’s surface g = 9.8. What is g at altitude equal to Earth’s radius (r = 2R)?
2.45
Two vectors, 5 N east and 12 N north, act on a body. What is the direction of the resultant relative to east?
67.4° N of E
A projectile is launched at 30 m/s at 40° above horizontal. What is its initial vertical velocity?
19.3 m/s
A 5 kg block slides frictionlessly down a 30° incline. What is its acceleration?
4.9 m/s^2
Determine the orbital speed of a satellite in low Earth orbit (r=6.7x10^6 m)
7.8 km/s
A planet has mass 4×10²⁴ kg and radius 3×10⁶ m. What is surface g?
29.6 m/s²