CIE M1 MECHANICS Questions

[xxemoxx]

Q) light travels at  a speed of 3.00*10^8 ms ^-1. light from the star sirius takes 8.65 years to reach the earth. what is the distance of sirius from the earth in kilometres?

Q) The guns were at the battle of the english fleet against the Dutch off the kent coast, a distance of between 110 and 120 km away. The speed of sound in air is 344ms^-1. How long did it take the sound of the gunfire to reach London?

[astarmathsandphysics]

When I get well. I feel sick.

[astarmathsandphysics]

Q) light travels at  a speed of 3.00*10^8 ms ^-1. light from the star sirius takes 8.65 years to reach the earth. what is the distance of sirius from the earth in kilometres?

Q) The guns were at the battle of the english fleet against the Dutch off the kent coast, a distance of between 110 and 120 km away. The speed of sound in air is 344ms^-1. How long did it take the sound of the gunfire to reach London?

Q)8.65 lightyears=3*10^8*3.15*10^7=8.65*9.56*10^15=8.18*10^16m

Q)average of 110 and 120=115km
t=d/v=115000/344=334seconds

[xxemoxx]

A ball is thrown upwards with and initial velocity of 15.5. for how long is the ball higher than 10.5 metres?

Q2 ) A ball is thrown upwards with an initial velocity of 12 from a point 2.5 metres above the ground. find the time when the ball reaches the ground and the velocity of the ball at this instant.

[astarmathsandphysics]

When I get home

[astarmathsandphysics]

A ball is thrown upwards with and initial velocity of 15.5. for how long is the ball higher than 10.5 metres?

Q2 ) A ball is thrown upwards with an initial velocity of 12 from a point 2.5 metres above the ground. find the time when the ball reaches the ground and the velocity of the ball at this instant.

Q1)s=ut+1/2at^2>10.5
15.5t-4.9t^2>10.5
0>4.9t^2-15.5t+10.5
t=0.98 or 2.18 so the ball is 105m above the ground at these times
ANS=2.18-0.98=1.2s

Q2)v^2=u^2+2as
v^2=12^2+2*-9.8*-2.5=193
v=-sqrt(193)=-13.9
t=(v-u)/a=(-13.9-13.9)/(-9.8)2.6 secs