Units & Measurements
What is the SI base unit for amount of substance?
Name 1 vector quantity and 1 scalar quantity
Ex vector: velocity, displacement, force
Ex scalar: speed, time, temperature
Convert 58 degrees to radians
58 degrees X (2π rad/360 dgress) = 1.01 rad
State Newton’s First Law of Motion.
An object remains at rest or moves at constant velocity unless acted on by a net external force.
Define momentum.
Product of mass and velocity (p=mvp = mvp=mv).
Calculate 4 x 1010 ÷ 5 x103
Give answer in standard form
4 x 1010 ÷ 5 x103
= 4 ÷ 5 = 0.8
1010-2 = 107
0.8 x 107 = 8x106
A toy car has an initial velocity of 6m/s and accelerates at 10.3 m/s2 for 3.8 s what is the distance covered by the car? Give answer to 3 sf
s = ut + 0.5at2
= 97.2 m
Name the force that keeps an object moving in a circle.
Centripetal force
In deep space g = 0 hence W = 0
What is impulse, and what are its units?
Change in momentum; units: N·s or kg·m/s.
Convert 50 Mg to mg
50 Mg x (1 x 106 g/1Mg) x (1000 mg/1g) = 5 x1010 mg
A ball moves from 5 m to 20 m in 3 s. Find its average velocity.
(20−5)/3=5m/s
What is the angular displacement of an object rotating around a circular track with radius 6.9 cm tracing an arc length of 10.3 cm
Angular displacement = s/r = 10.3 cm/6.9 cm = 1.49 rad
What is the net force on a 5 kg object accelerating at 3 m/s²?
F=ma=5(3)=15N
Calculate the momentum of an object with mass 500 kg and velocity 2.5 m/s
p = mv = 500kg x 2.5 m/s = 1250 kgm/s
List 4 fundamental quantities
mass, length, time, temperature, amount of substance, current, luminous intensity
A car accelerates from 10 m/s to 25 m/s in 5 s. What is its acceleration?
(25−10)/5=3m/s2
A 0.5 kg ball moves in a circle of radius 50 cm with a period of 0.15 s. Find the tangential speed. Give the answer to 1 decimal place
v = 2πr/ T = 2π(0.5m)/0.15s = 20.9 m/s
A force of 50 mN is applied causing an acceleration of 2.6 m/s2. What is the mass of the object? Give ans to 3 sf
F = 50 mN x (1N/1000 mN) = 0.05 N
m = F÷ a = 0.05 N/2.6 m/s2 = 0.019 kg
A 4kg block moving at 3 m/s collides with a stationary block of mass 10 kg. After collision they move together what is their final velocity?
Total momentum before = total momentum after
m1u1 + m2u2 = (m1 + m2)v
(4kg)(3m/s) = (4 + 10)v
v = 12kgm/s/14 kg m/s = 0.86 m/s
Power = Work done/time
Work done = Fd
What is the SI BASE unit of Power
Power = Fd/t = mad/t = kgm/s2 m ÷ s = kgm2s-3
A train starts from rest and accelerates at 2 m/s² for 10 s. How far does it travel?
s=(1/2)at2=0.5(2)(10)2=100m
An object of mass 500 g is attached to a string with radius 20 cm if the period for one oscillation is 0.8 s what is the centripetal force? (Give answer to 3 sf)
F = mac = m4π2r/ T2 = (0.5 kg)4 π2 (0.2m)/(0.8s)2
= 6.17 N
What force must an object of weight 5.6 N apply to generate an acceleration of 3.5 m/s2?
W = mg m = W/g = 5.6 N/9.8 m/s2 = 0.57 kg
F = ma = 0.57 kg x 3.5 m/s2 = 2 N
A 0.15 kg baseball moving at 40 m/s is caught in 0.2 s. What is the average force exerted by the glove?
F=ΔtΔp=0.15(40)/0.2=30N