Units and Measurements
What is the SI base unit for amount of substance?
mole (mol)
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 (2n rad/360 degrees) = 1.01 rad
State Newton's Second Law of Motion.
F = ma
Define momentum
Product of mass and velocity (p=mv).
Calculate 4 x1010 ÷ 5 x 103
Give the answer in standard form
4 x 1010 ÷ 5 x 103
= 4 ÷ 5 = 0.8
= 1010-2 = 107
= 0.8 x 107
= 8 x 106
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 = (6m/s)(3.8s) + 0.5(10.3 m/s2)(3.8s)2
= 97.2 m
Name the force that keeps an object moving in a circle.
Centripetal force
What is the weight Of a 55 kg man in deep space?
In deep space g = 0 hence W = 0 N
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/1 Mg) x (1000 mg/1g)
= 5 x 1010 mg
A ball moves from 5 m to 20 m in 3s. Find its velocity.
v = Δ s/t = (20m-5m)/3s = 5 m/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 kg x 3 m/s2 = 15 N
Calculate the momentum of an object with mass 500 kg and velocity 2.5 m/s.
p = mv = 5000 kg 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?
a= v-u/t = (25-10)ms-1/5s = 3m/s2
A 0.5 kg ball moves In a circle of radius 50 cm with a period of O. 15 s. Find the tangential speed. Give the answer to 1 decimal place
v = 2πr/T = 2π(0.5m)/0.15 s = 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
12kgms-1/14 kg m/s = v
= 0.86m/s
Power = Work done/time
Work done = Force x distance
What is the SI BASE unit of Power?
P = W/t = Fd/t = mad/t = kgm/s2 x m ÷ s = kgm2s-3
A train starts from rest and accelerates at 2 m/s2 for 10 s. How far does it travel?
s = u + (1/2)at2
= (1/2)at2
= (0.5)(2m/s2)(10s)2
= 100 m
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 =mv2/r = m4π2r/T2 = (0.5kg)4π2(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 = 2N
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?
Ft = mv
F = mv/t
= (0.15kg)(40 m/s)/(0.2s)
= 30 N