Back
to top
mechanics questions help plss!!!
Watch this threadPage 1 of 1
Go to first unread
Skip to page:
luce1411
Badges:
2
Rep:
?
You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#1
hii I'm really struggling with these questions we got set for homework. can anyone help out with these alevel mechanics questions?? literally my last hope 😭
1 A rough plane is inclined to the horizontal at an angle a, where tan a = 3/4. A brick P of mass m is placed on the plane.
The coefficient of friction between P and the plane is mu
Brick P is in equilibrium and on the point of sliding down the plane.
Brick P is modelled as a particle. Using the model
(a) find, in terms of m and g , the magnitude of the normal reaction of the plane on brick P ( b) show that mu = 3/4
2 A particle P moves with acceleration (4i - 5j) ms - 2
At time t = 0 , P moving with velocity (- 2i + 2j)ms-1
(a) Find the velocity of at time t = 2 seconds.
3 At time t seconds , where t >= 0 , a particle P moves so that its acceleration a ms-2 is given by
a = (1 - 4t) i + (3 - t ^ 2) j
At the instant when t = 0 , the velocity of P is 36i ms-1
(a ) Find the velocity of P when t = 4
much appreciated yall 😽✌️
1 A rough plane is inclined to the horizontal at an angle a, where tan a = 3/4. A brick P of mass m is placed on the plane.
The coefficient of friction between P and the plane is mu
Brick P is in equilibrium and on the point of sliding down the plane.
Brick P is modelled as a particle. Using the model
(a) find, in terms of m and g , the magnitude of the normal reaction of the plane on brick P ( b) show that mu = 3/4
2 A particle P moves with acceleration (4i - 5j) ms - 2
At time t = 0 , P moving with velocity (- 2i + 2j)ms-1
(a) Find the velocity of at time t = 2 seconds.
3 At time t seconds , where t >= 0 , a particle P moves so that its acceleration a ms-2 is given by
a = (1 - 4t) i + (3 - t ^ 2) j
At the instant when t = 0 , the velocity of P is 36i ms-1
(a ) Find the velocity of P when t = 4
much appreciated yall 😽✌️
0
reply
ZR2002
Badges:
10
Rep:
?
You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#2
Report
#2
for 1- you know that the normal reaction is equal to mgcos a and you can use inverse tan a to get a then put it into cos to get an answer. for part b you know that mgsina is equal to friction as the particle is in equillibrium so you know that mu x normal reaction is equal to mgsina. so you rearrange to find mu
1
reply
ZR2002
Badges:
10
Rep:
?
You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#3
Report
#3
2 A particle P moves with acceleration (4i - 5j) ms - 2
At time t = 0 , P moving with velocity (- 2i + 2j)ms-1
(a) Find the velocity of at time t = 2 seconds.
for this one, you use v=u+at. u is (- 2i + 2j)ms-1, you have a and you put in t=2 to get v
At time t = 0 , P moving with velocity (- 2i + 2j)ms-1
(a) Find the velocity of at time t = 2 seconds.
for this one, you use v=u+at. u is (- 2i + 2j)ms-1, you have a and you put in t=2 to get v
0
reply
ZR2002
Badges:
10
Rep:
?
You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#4
Report
#4
3 At time t seconds , where t >= 0 , a particle P moves so that its acceleration a ms-2 is given by
a = (1 - 4t) i + (3 - t ^ 2) j
At the instant when t = 0 , the velocity of P is 36i ms-1
(a ) Find the velocity of P when t = 4
same thing here i think but you have a, t and u so you do u+ at to get v .
a = (1 - 4t) i + (3 - t ^ 2) j
At the instant when t = 0 , the velocity of P is 36i ms-1
(a ) Find the velocity of P when t = 4
same thing here i think but you have a, t and u so you do u+ at to get v .
0
reply
luce1411
Badges:
2
Rep:
?
You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#5
hii thank you so much for your help I'm super grateful!! do you think you could help with these 2 questions as well? would be much appreciated 
A ladder AB has mass M and length 6a.
The end A of the ladder is on rough horizontal ground.
The ladder rests against a fixed smooth horizontal rail at the point C.
The point C is at a vertical height 4a above the ground.
The vertical plane containing AB is perpendicular to the rail.
The ladder is inclined to the horizontal at an angle a, where sin a= 4/5,, as shown in Figure 1.
The coefficient of friction between the ladder and the ground is u.
The ladder rests in limiting equilibrium.
The ladder is modelled as a uniform rod.
Using the model,
(a) show that the magnitude of the force exerted on the ladder by the rail at C is 9Mg/25
(6) Hence, or otherwise, find the value of mu.
A small ball is projected with speed Ums from a point O at the top of a vertical cliff.
The point is 25 m vertically above the point N which is on horizontal ground.
The ball is projected at an angle of 45° above the horizontal.
The ball hits the ground at a point A, where AN= 100 m, as shown in Figure 2.
The motion of the ball is modelled as that of a particle moving freely under gravity.
Using this initial model,
(a) show that U28
(b) find the greatest height of the ball above the horizontal ground NA.
In a refinenment to the model of the motion of the ball from O to A, the effect of air
resistance is included.
This refined model is used to find a new value of U.
(c) How would this new value of U compare with 28, the value given in part (a)?
(d) State one further refinement to the model that would make the model more realistic.
A ladder AB has mass M and length 6a.
The end A of the ladder is on rough horizontal ground.
The ladder rests against a fixed smooth horizontal rail at the point C.
The point C is at a vertical height 4a above the ground.
The vertical plane containing AB is perpendicular to the rail.
The ladder is inclined to the horizontal at an angle a, where sin a= 4/5,, as shown in Figure 1.
The coefficient of friction between the ladder and the ground is u.
The ladder rests in limiting equilibrium.
The ladder is modelled as a uniform rod.
Using the model,
(a) show that the magnitude of the force exerted on the ladder by the rail at C is 9Mg/25
(6) Hence, or otherwise, find the value of mu.
A small ball is projected with speed Ums from a point O at the top of a vertical cliff.
The point is 25 m vertically above the point N which is on horizontal ground.
The ball is projected at an angle of 45° above the horizontal.
The ball hits the ground at a point A, where AN= 100 m, as shown in Figure 2.
The motion of the ball is modelled as that of a particle moving freely under gravity.
Using this initial model,
(a) show that U28
(b) find the greatest height of the ball above the horizontal ground NA.
In a refinenment to the model of the motion of the ball from O to A, the effect of air
resistance is included.
This refined model is used to find a new value of U.
(c) How would this new value of U compare with 28, the value given in part (a)?
(d) State one further refinement to the model that would make the model more realistic.
0
reply
YuvrajRam
Badges:
7
Rep:
?
You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#6
Report
#6
(Original post by luce1411)
hii thank you so much for your help I'm super grateful!! do you think you could help with these 2 questions as well? would be much appreciated
A ladder AB has mass M and length 6a.
The end A of the ladder is on rough horizontal ground.
The ladder rests against a fixed smooth horizontal rail at the point C.
The point C is at a vertical height 4a above the ground.
The vertical plane containing AB is perpendicular to the rail.
The ladder is inclined to the horizontal at an angle a, where sin a= 4/5,, as shown in Figure 1.
The coefficient of friction between the ladder and the ground is u.
The ladder rests in limiting equilibrium.
The ladder is modelled as a uniform rod.
Using the model,
(a) show that the magnitude of the force exerted on the ladder by the rail at C is 9Mg/25
(6) Hence, or otherwise, find the value of mu.
A small ball is projected with speed Ums from a point O at the top of a vertical cliff.
The point is 25 m vertically above the point N which is on horizontal ground.
The ball is projected at an angle of 45° above the horizontal.
The ball hits the ground at a point A, where AN= 100 m, as shown in Figure 2.
The motion of the ball is modelled as that of a particle moving freely under gravity.
Using this initial model,
(a) show that U28
(b) find the greatest height of the ball above the horizontal ground NA.
In a refinenment to the model of the motion of the ball from O to A, the effect of air
resistance is included.
This refined model is used to find a new value of U.
(c) How would this new value of U compare with 28, the value given in part (a)?
(d) State one further refinement to the model that would make the model more realistic.
hii thank you so much for your help I'm super grateful!! do you think you could help with these 2 questions as well? would be much appreciated
A ladder AB has mass M and length 6a.
The end A of the ladder is on rough horizontal ground.
The ladder rests against a fixed smooth horizontal rail at the point C.
The point C is at a vertical height 4a above the ground.
The vertical plane containing AB is perpendicular to the rail.
The ladder is inclined to the horizontal at an angle a, where sin a= 4/5,, as shown in Figure 1.
The coefficient of friction between the ladder and the ground is u.
The ladder rests in limiting equilibrium.
The ladder is modelled as a uniform rod.
Using the model,
(a) show that the magnitude of the force exerted on the ladder by the rail at C is 9Mg/25
(6) Hence, or otherwise, find the value of mu.
A small ball is projected with speed Ums from a point O at the top of a vertical cliff.
The point is 25 m vertically above the point N which is on horizontal ground.
The ball is projected at an angle of 45° above the horizontal.
The ball hits the ground at a point A, where AN= 100 m, as shown in Figure 2.
The motion of the ball is modelled as that of a particle moving freely under gravity.
Using this initial model,
(a) show that U28
(b) find the greatest height of the ball above the horizontal ground NA.
In a refinenment to the model of the motion of the ball from O to A, the effect of air
resistance is included.
This refined model is used to find a new value of U.
(c) How would this new value of U compare with 28, the value given in part (a)?
(d) State one further refinement to the model that would make the model more realistic.
0
reply
X
Page 1 of 1
Go to first unread
Skip to page:
Quick Reply
